If you control another Kess thanks to Spark Double, the number of instant and/or sorcery spells you may cast from your graveyard "[d]uring each of your turns" is increased by one while that Kess remains on the battlefield (C.R. 611.3b, 113.6).
(In general, if two or more effects allow you to cast a spell in a manner not otherwise allowed — e.g., if you control two permanents that have Kess's second ability — you should announce which such effect to make use of as you cast that spell, in case of ambiguity.)
EDIT (Jun. 8): Edited to conform to update with Ikoria: Lair of Behemoths.
EDIT (Dec. 31, 2020): Clarification.
(611.3b The effect applies at all times that the permanent generating it is on the battlefield or the object generating it is in the appropriate zone.
Example: A permanent with the static ability “All white creatures get +1/+1” generates an effect that continuously gives +1/+1 to each white creature on the battlefield. If a creature becomes white, it gets this bonus; a creature that stops being white loses it.)
113.6 Abilities of an instant or sorcery spell usually function only while that object is on the stack. Abilities of all other objects usually function only while that object is on the battlefield. The exceptions are as follows:
113.6a Characteristic-defining abilities function everywhere, even outside the game. (See rule 604.3.)
113.6b An ability that states which zones it functions in functions only from those zones.
113.6c An object’s ability that allows a player to pay an alternative cost rather than its mana or otherwise modifies what that particular object costs to cast functions on the stack.
113.6d An object’s ability that restricts or modifies how that particular object can be played or cast functions in any zone from which it could be played or cast and also on the stack. An object’s ability that grants it another ability that restricts or modifies how that particular object can be played or cast functions only on the stack.
113.6e An object’s ability that restricts or modifies what zones that particular object can be played or cast from functions everywhere, even outside the game.
113.6f An object’s ability that states it can’t be countered functions on the stack.
113.6g An object’s ability that modifies how that particular object enters the battlefield functions as that object is entering the battlefield. See rule 614.12.
113.6h An object’s ability that states counters can’t be put on that object functions as that object is entering the battlefield in addition to functioning while that object is on the battlefield.
113.6i An object’s activated ability that has a cost that can’t be paid while the object is on the battlefield functions from any zone in which its cost can be paid.
113.6j A trigger condition that can’t trigger from the battlefield functions in all zones it can trigger from. Other trigger conditions of the same triggered ability may function in different zones.
Example: Absolver Thrull has the ability “When Absolver Thrull enters the battlefield or the creature it haunts dies, destroy target enchantment.” The first trigger condition functions from the battlefield and the second trigger condition functions from the exile zone. (See rule 702.54, “Haunt.”)
113.6k An ability whose cost or effect specifies that it moves the object it’s on out of a particular zone functions only in that zone, unless its trigger condition or a previous part of its cost or effect specifies that the object is put into that zone or, if the object is an Aura, that the object it enchants leaves the battlefield. The same is true if the effect of that ability creates a delayed triggered ability whose effect moves the object out of a particular zone.
Example: Reassembling Skeleton says “{1}{B}: Return Reassembling Skeleton from your graveyard to the battlefield tapped.” A player may activate this ability only if Reassembling Skeleton is in his or her graveyard.
113.6m An ability that modifies the rules for deck construction functions before the game begins. Such an ability modifies not just the Comprehensive Rules, but also the Magic: The Gathering Tournament Rules and any other documents that set the deck construction rules for a specific format. However, such an ability can’t affect the format legality of a card, including whether it’s banned or restricted. The current Magic: The Gathering Tournament Rules can be found at WPN.Wizards.com/en/resources/rules-documents.
113.6n Abilities of emblems, plane cards, vanguard cards, scheme cards, and conspiracy cards function in the command zone. See rule 114, “Emblems”; rule 901, “Planechase”; rule 902, “Vanguard”; rule 904, “Archenemy”; and rule 905, “Conspiracy Draft.”
When you use an instant or a sorcery from your graveyard using Original Kess targeting an spell, then the other will not see the same ability "triggering" the text "During each of your turns, you may cast an instant or a sorcery from your graveyard"?
When you use an instant or a sorcery from your graveyard using Original Kess targeting an spell, then the other will not see the same ability "triggering" the text "During each of your turns, you may cast an instant or a sorcery from your graveyard"?
Each ability has a separate effect and functions independently of any other ability, even if both abilities have the same text (see also C.R. 113.2c). For example, in general, if you control two permanents that have Kess's second ability, you may cast two instant and/or sorcery spells from your graveyard "[d]uring each of your turns", because there are two effects each letting you "cast an instant or sorcery spell from your graveyard". Making use of one doesn't cancel the other. (See also this thread.) Note that Kess's second ability is not a triggered ability, since it doesn't start with "when", "at", or "whenever" (C.R. 603.1).
EDIT (Jun. 8): Edited to conform to update with Ikoria: Lair of Behemoths.
EDIT (Sep. 28, 2020): Edited.
EDIT (Dec. 31, 2020): Clarification.
Spark Double is a hell of a new card and I have my doubts about it.
If I copy Kess, Dissident Mage I have 2 activations into my graveyard?
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-MadMage
(In general, if two or more effects allow you to cast a spell in a manner not otherwise allowed — e.g., if you control two permanents that have Kess's second ability — you should announce which such effect to make use of as you cast that spell, in case of ambiguity.)
EDIT (Jun. 8): Edited to conform to update with Ikoria: Lair of Behemoths.
EDIT (Dec. 31, 2020): Clarification.
Example: A permanent with the static ability “All white creatures get +1/+1” generates an effect that continuously gives +1/+1 to each white creature on the battlefield. If a creature becomes white, it gets this bonus; a creature that stops being white loses it.)
113.6 Abilities of an instant or sorcery spell usually function only while that object is on the stack. Abilities of all other objects usually function only while that object is on the battlefield. The exceptions are as follows:
113.6a Characteristic-defining abilities function everywhere, even outside the game. (See rule 604.3.)
113.6b An ability that states which zones it functions in functions only from those zones.
113.6c An object’s ability that allows a player to pay an alternative cost rather than its mana or otherwise modifies what that particular object costs to cast functions on the stack.
113.6d An object’s ability that restricts or modifies how that particular object can be played or cast functions in any zone from which it could be played or cast and also on the stack. An object’s ability that grants it another ability that restricts or modifies how that particular object can be played or cast functions only on the stack.
113.6e An object’s ability that restricts or modifies what zones that particular object can be played or cast from functions everywhere, even outside the game.
113.6f An object’s ability that states it can’t be countered functions on the stack.
113.6g An object’s ability that modifies how that particular object enters the battlefield functions as that object is entering the battlefield. See rule 614.12.
113.6h An object’s ability that states counters can’t be put on that object functions as that object is entering the battlefield in addition to functioning while that object is on the battlefield.
113.6i An object’s activated ability that has a cost that can’t be paid while the object is on the battlefield functions from any zone in which its cost can be paid.
113.6j A trigger condition that can’t trigger from the battlefield functions in all zones it can trigger from. Other trigger conditions of the same triggered ability may function in different zones.
Example: Absolver Thrull has the ability “When Absolver Thrull enters the battlefield or the creature it haunts dies, destroy target enchantment.” The first trigger condition functions from the battlefield and the second trigger condition functions from the exile zone. (See rule 702.54, “Haunt.”)
113.6k An ability whose cost or effect specifies that it moves the object it’s on out of a particular zone functions only in that zone, unless its trigger condition or a previous part of its cost or effect specifies that the object is put into that zone or, if the object is an Aura, that the object it enchants leaves the battlefield. The same is true if the effect of that ability creates a delayed triggered ability whose effect moves the object out of a particular zone.
Example: Reassembling Skeleton says “{1}{B}: Return Reassembling Skeleton from your graveyard to the battlefield tapped.” A player may activate this ability only if Reassembling Skeleton is in his or her graveyard.
113.6m An ability that modifies the rules for deck construction functions before the game begins. Such an ability modifies not just the Comprehensive Rules, but also the Magic: The Gathering Tournament Rules and any other documents that set the deck construction rules for a specific format. However, such an ability can’t affect the format legality of a card, including whether it’s banned or restricted. The current Magic: The Gathering Tournament Rules can be found at WPN.Wizards.com/en/resources/rules-documents.
113.6n Abilities of emblems, plane cards, vanguard cards, scheme cards, and conspiracy cards function in the command zone. See rule 114, “Emblems”; rule 901, “Planechase”; rule 902, “Vanguard”; rule 904, “Archenemy”; and rule 905, “Conspiracy Draft.”
EDIT (Jun. 8): Edited to conform to update with Ikoria: Lair of Behemoths.
EDIT (Sep. 28, 2020): Edited.
EDIT (Dec. 31, 2020): Clarification.