Music changes after duplicating sequences

Hey all,
I've noticed this problem every now and then. I'll be working away on a cut, send off to the client, get changes back, then duplicate the last sequence I was working on and go from there. What's odd is that somehow the music gets all screwy in the new sequence even though nothing has changed.

Screwy might be a bad term, but basically the music will be playing, and looks fine in the waveform, but it suddenly plays a totally different part of the song then what it should. When that happens, I have to go back to the original music file in FCP and re-cut it in that spot. So it's only the track in the sequence that gets messed up, not the original file. It's so completely bizarre. I have no idea why that happens or what causes it, and it doesn't happen all the time. But the problem is, I always have to check the music is ok with each new sequence and that's time consuming. Duplicating shouldn't screw anything up.

Anyone have any thoughts or experienced this themselves? Thanks!