I am having a problem with using work offsets in Mach3. I have set up 4 offsets, and they run fine, with one exception. The roughing passes cut the workpiece that is in the first position(G54) too deep. The cutter does not run uniformly too deep, it only cuts too deep on curved geometry. The best way I can think of to illustrate what it does is: if you were to lay a mesh over the workpiece after it's done being roughed, the mesh would rest on the high points left by the cutter, and create a surface at the correct finished height. but because the cutter is square, it cuts out too much material in between its high points. (Hope that's clear as mud, having a hard time describing it)
If I cut the part individually, it runs fine. I am simply taking the completed toolpaths for the parts being cut at the different offsets, and copying and pasting them into one file. What's really confusing me is that there is NO editing done to the toolpaths on the first part. The subsequent parts toolpaths require editing so that the mill will run without interruption. I thought maybe I wasn't getting a good zero, but I am consistently having the same problem, and the other 3 parts run fine.
Really not sure what's going on here, any insight would be greatly appreciated.

Thank you