Currently in dDup if you merge A>B, then merge B>C, dDup will update the original result and change A>C.

If you later reset the B>C result, it seems that dDup should undo that second "chained" merge and return A>B.   Currently it just leaves A>C which may be totally wrong.

I think you would have to capture a History of merges with some order so you could revert the result back to the result immediately prior to whatever you last reset.

1.  Merge A>B

2.  Merge B>C

2a.  Updates A>C

3.  Reset B<>C

3a. Update A>B since this was the result prior to step 2.