Julian…
right…what you are used to is FCP treating every track as mono
Ppro can do that, but it’s default behavior is to include stereo tracks in the sequence as well. (all this can be customized)
If you can get to looking at the waveform in the track you will lilkely notice that you will actually see both left and right waveforms within one track (noting that it’s a stereo track)
Since you can’t place a stereo source to a mono track, or vice versa, premiere is using first available track of matching type…
Right clicking on the track label area should give you the ability to add additional tracks of both audio and video. read that dialog carefully, can be a little tricky.
Alex