code:
_root["dupedmc"+i]


^ this means you'll target things like:

_root.dupedmc1
_root.dupedmc2
_root.dupedmc3
_root.dupedmc4
...etc

code:
_root.dupedmc[i]


^ this means you'll target things like:

_root.dupedmc.MC1
_root.dupedmc.MC2
_root.dupedmc.MC3
_root.dupedmc.MC4
...etc


ANYWAY, did you specify anything for "i" when you perform your hitTest? a for loop in your case...