So a bunch of minions (in XP amounts) is actually a fewer amount of guys. It is just they keep getting knocked away and coming back later after recovering.
FS: I hope I'm understanding you correctly. By this you will have say 10 minions, but only 5 bodies. After each is reduced to zero they will be replaced by the next? If that was your intent that is very cool. I will definately be doing that for undead minions. I can't wait to see the look on my players faces when I tell them the zombie whos body was split in half crawls toward them to bite *munch munch*