From the rules on Panther Parry:
"...If your retaliatory unarmed strike deals damage to an opponent, that opponent takes a –2 penalty on attack and damage rolls with the triggering attack of opportunity."
Panther Claw, a pre-req for Panther Parry, allows you multiple retaliatory strikes. Does the -2 penalty on attack and damage rolls stack? i.e. If a player manages to deal damage to an opponent twice with retaliatory strikes, does the opponent take a -4 penalty on attack and damage rolls for the AOO?
On the rare (I can't fathom one)occasion that an enemy could provoke more than one AOO for a single attack, I'd say "no" they -2 penalty is coming from the same source.
You realize the Panther Claw feat "You can make a number of retaliatory unarmed strikes on your turn equal to your Wisdom modifier." Means you are no longer limited by the 1 swift action per round for AOO's you intentionally provoke with Panther Style, so you can move past multiple enemies and activate your retaliations against all of them, it doesn't mean a single enemy swings at you and you get to hit him 5 times, right?
The limitations of combat reflexes still applies
"Combat Reflexes and Additional Attacks of Opportunity: If you have the Combat Reflexes feat, you can add your Dexterity modifier to the number of attacks of opportunity you can make in a round. This feat does not let you make more than one attack for a given opportunity, but if the same opponent provokes two attacks of opportunity from you, you could make two separate attacks of opportunity (since each one represents a different opportunity). Moving out of more than one square threatened by the same opponent in the same round doesn't count as more than one opportunity for that opponent. All these attacks are at your full normal attack bonus."
