Folder creation upon BibTex import doesn't work if the references already exist in the library

I have a BibTex file of ~250 citations and want to merge with my Paperpile citations, and I know that all of these citations exist in my library. It’s more that this file is a list of references I would like in one place. Unfortunately, when I import the BibTex file, the folder is empty! And the reason I get is because the citations already exist. This is not what I expected. If I say to make a folder from a BibTex file, shouldn’t it put all the references that match, into the new folder?