The other day, I came across a very bizarre problem. All I was doing was copying and pasting between drawings, but the entities were being pasted into the other drawing a different scale!
Having not encountered this before, I assumed it was something to do with units, so I typed the UNITS command. But to my surprise, all was as it should be, which meant something else was causing the problem.
It turns out the fix was in a discrepency between the values accessibly by -DWGUNITS. So if you ever have this problem, that’s the fix.
Hope this helps,