Hi,
Stereo samples does'nt show as two waveforms side by side, but both channels should sound.
Have you tried to import a stereo sample with a very clear left and right? You should be able to hear this.
If you change the sample using "convert to synthesis", then there will be differences, if you use the L+R channel setting or not, and thus indicate if you have both the L and the R sound data.
Can't tell if it also depend on the used file.