aren't you mixing up double-rename here? The "allow double rename option" only checks if two old sets are renamed to the same new one.
So generally, no restrictions to parent/clone renaming should be done when creating the rename list...don't care for double of parent/clone renames....that list should stay the same...
...but when applying the renames to a nother dat, it should avoid double-renaming (i.e. not creating two equally named pngs...) and handle parent/clone handling (where the parent/clone relationships come from the old/new dats and not the 3rd-to-be-modified dat....which is a bit...hmm...annoying
)