We claimed two at once. Lost both heads, received only one reward, no one received XP. One person in the party turned out to be too low level for the quest, but the others weren't.
Bounty Quest
P.S. I can't remember to log in before I post like a normal person.
Having no XP reward makes sense somewhat, since in theory you could have one group kill the NPC, then give the head to someone else to claim the reward. That sounds like an exploit though.
Don't try this at home, kids!
Which is why it's a bug, adharmas. >_> You're supposed to take the quest first, anyway, since that sets all the bounty heads hostile to the quest takers. In turn, that prevents the exploit you mentioned (but if memory serves, force-attacking doesn't mess up factions, so you can easily kill the bounty heads without taking the quest first).
This quest has been like this the last couple of times I did it.
Thrawn!
Thrawn? >_>