If you merge page A with page B, only B will remain, and A will be an for B.
Merge will also append A's content to the bottom of B. That way no content is lost.
Detect duplicates to merge
Similar pages could be merged
Compare pages before merging
I need to merge Film lists and My movie lists
would also merge all Internal links to point to the one thing
Two different page titles being merged would keep the linked instances the same as they were since those should now included in the Alternative titles