What is that second copy of the retopologized object? Why are we copying the "combined" version of the UVs to it?
I'm simply "transferring UV maps" from one object with UVs to a duplicate of the object (same mesh) without UVs. I duplicated the entire stack of rocks to layout UVs together into a consolidated map because in order to lay out all their UVs together they need to be combined as one object. I want a consolidated UV map so all the individual rocks can share a single texture.
I left the original stack of separate rocks so I could separate the duplicate stack of UV'd rocks and transfer UVs from each individual duplicate rock to it's counterpart.