Bug reports & end-user support for Akai's MPC Software 'controllers' including the new MPC Studio 2, the MPC Touch, MPC Renaissance & original MPC Studio and MPC StudioB lack.
You can also go to Sampler and change the input to resample. That will record anything playing in the MPC sequencer. There are some other options, include a easy way I just can't remember it.
In Maschine you can record 2 or more pads to 1 pad, i'm sure there is an option like that in the MPC software I just can't remember it.
Other than resampling sequencer output there's currently no easy way to achieve this in the MPC as the audio editing features are still fairly basic. I believe in 2.0 it might be possible to copy/paste audio within an audio track, not sure if this will work in SAMPLE EDIT mode.