EZdrummer 3 Question/issue

[Scott]

When I start a track, I'll insert EZdrummer and stretch it out (groove clip looping) longer than I'll need to be safe.  Once I'm done recording, I'll then delete the leftover drum track at the end.  I'll then mix everything and export it out to my PC desktop in a wave file.  I'll then import it back in as a stereo track (after my initial mixdown).  I'll apply a mastering plugin and do the final touches at the end of the track.  I notice that even though I deleted the drums at the end of the track, there is this 2 line (what I call) drum residue.  I'll then delete that and all is good.  Sometimes when I go to delete the unused drums, I find the groove clip looping has taken the drum track MUCH farther than I initially  set it.  Anyone have any experience with this? And, why does it happen?

Thanks