Copy and paste adds length to clip

[BrandonUnis]

Apologies if this has been covered before but I did some searching and couldn't find the solution or any discussion.

I'm trying to copy and paste 16 bars of music a few times over. By the time I loop the same clips on my edit page 3 times, there is a noticeable change in the start and stop point of the loops.

I know for sure my first 16 bars start and end perfectly on grid but just 1:30 later it is off grid.. there must be a fix to this. Running protools 12.8 on a brand new mac laptop. photo attached to show what is happening.

Thanks!