Sequential circuits samplers

I have a P2K that I picked up (as some of you may recall) at a music store 
tent sale for $10. It works fine, and it has 512k memory. But it does 
something I find strange, and I want to find out if it's normal or not.
When I listen in Stereo (for example, with headphones in the headphone 
jack) and play one note over and over (either from a preset or a loaded 
disk) I hear 4 notes in one ear, 4 in the other, and then it repeats that. 
If I play a chord, some of the notes sound in one ear, and some in the 
other, and I never know which notes will be in which ear (it changes each 
time I play the chord). In mono, it sounds perfectly normal. It has OS 
version 3.0 (I have 4.3 on order).
Is what I described normal, and if not, what could be the cause?
-- Pat