Hi abc,
With the latest versions of JJ OS you could do what is suggested above by peterpiper in a more "non-destructive" way.
For instance with JJOS2XL :
For only one sample : copy it, choose L play mode for one sample and R for the other in program mode, simult2 these samples, in trim mode adjust starts points.
For several chops :
- copy the original sample
- delete only L or R for the samples in trim edit
- in trim mode put non destructive chop (NDC) on with the same settings for the two samples
- in program mode assign these two samples several times with the right NDC chop numbers.
- simult2 them in program mode as well
- finally change the start and end points with non-destructive chop in trim mode.
There's is an fkey that allows to switch to program mode in trim mode. It's very practical. The only drawback in this mode is you have to press the simulting pad again if you have just edited the simulted pad in order to hear them together.
With OS3 it's probably possible to do this without leaving program mode with non-destructive slice. I don't know this OS very much but I think there are many possible workarounds for what you want to do

Peace