d20Dwarf
Explorer
I dunno, I would only allow a trip and a single re-trip, since you've already used your "standing up" AoO for the round on that opponent. Of course, at that point you've screwed their round up and can just trip them again on your turn. 
As an aside, I do not allow the spiked chain in my games. It is the dumbest, most imbalanced weapon ever invented for the game. What are they thinking? Why do they want to turn the game into a spiked chain fest? Why didn't they fix this weapon that is greater than even any other exotic weapon in the game?

As an aside, I do not allow the spiked chain in my games. It is the dumbest, most imbalanced weapon ever invented for the game. What are they thinking? Why do they want to turn the game into a spiked chain fest? Why didn't they fix this weapon that is greater than even any other exotic weapon in the game?