Merge book by error

Hello,

I was editing my tags and did a kind of drag and drop from a book to another. And by error I clicked on "Return" button before noticing it.

So I validated the window asking if I want to merge 2 books.

Were checked:
Merge Metadata
Merge formats
Delete Merged books

Is there a way to identify which book was merge on which one (some logs maybe) ?

Thank you