I know it's me to choose the order of the damage replacing effects. Can I choose Punish the Enemy deals 8 damage(double first, then plus 2) to me, and deals 10 damage (plus2 first, then double) to myHornet Nest. Or it must be the same order so that we take both 8 or both 10 damage?
Yes you can do this. For each instance of damage you choose which order replacement effects are applied. Note that for an effect that only deals damage once but to multiple things, such as earthquake, there is only one instance of damage.
Note that the comprehensive rules speak of "two or more replacement and/or prevention effects ... attempting to modify the way an event affects an object or player", suggesting that if a source deals damage to one or more objects and/or players at the same time, and two or more replacement effects apply to each such object or player, the appropriate player chooses separately for each such object or player which applicable replacement effect applies (C.R. 616.1). This is the case regardless of whether—
a source deals damage each to two or more objects and/or players, but the amount of damage varies with each of them (as in Punish the Enemy or Orcish Cannonade), or
a source deals the same amount of damage, specified only once, each to two or more objects and/or players (as in Earthquake or Pestilence's last ability).
I know it's me to choose the order of the damage replacing effects. Can I choose Punish the Enemy deals 8 damage(double first, then plus 2) to me, and deals 10 damage (plus2 first, then double) to myHornet Nest. Or it must be the same order so that we take both 8 or both 10 damage?
EDIT (Jan. 11, 2020): Edited.