um, if you rename and reload it, you use twice the memory. all the param settings can be applied to as many instances of the same sample on the mpc and it only needs to be loaded into memory once, and only takes up however big it is in ram, regardless of how many pads you assign it to with different settings.
to assign the sound to another pad simply:
go to the program assign screen shift+6 and hit the pad that contains the sound,
make a mental note of the name and hit the other pad you want to assign it to.
simply scroll the sound name (or none) for the new pad until it shows the name of the sample you want assigned.
for example lets say pad1 has sound called sound005
and you want it on pad5 too with different tuning
simply hit pad 5 and scroll til it shows sound005 next to it.
then go to the params screen and edit away. repeat as necassary. this is how the bass and flute patches on the original floppies that came with the mpc2000 were setup.