Yes, prowess is a triggered ability, so multiple instances of prowess trigger and resolve separately. If a creature has two instances of prowess, when both abilities resolve the creature will basically get +2/+2 until end of turn.
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Lapsed DCI Rules Advisor - Retired from playing but still hanging around
Prowess like Exalted is a triggered ability. These are always cumalative.
If you have multiple creatures with prowess abilities or a creature with prowess multiple times all of the abilities will fire if you cast a non creature spell.
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- H.L Mencken
I Became insane with long Intervals of horrible Sanity
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I'm not aware of any specific card that can cause a creature to gain prowess, though.
If you have multiple creatures with prowess abilities or a creature with prowess multiple times all of the abilities will fire if you cast a non creature spell.
- H.L Mencken
I Became insane with long Intervals of horrible Sanity
All Religion, my friend is simply evolved out of fraud, fear, greed, imagination and poetry.
- Edgar Allan Poe
The Crafters' Rules Guru