This topic is close to the following post but it is not exactly the same and the suggested in the following linksolution might not work:
The situation is as follows:
Assume there are 2 users (A & B) of a seafile server and they both have their own library of a project (Proj1). If user A transfer the ownership of Proj1 library to user B, we will have a situation of multiple libraries with the same name and same ownership. I have not tried this but hopefully this does not cause any confusion for the client (as been mentioned in the link above).
I want to suggest that Seafile marks transferred libraries with a flag, so that user knows what has come from else where (since user has no control of receiving ownership and they cannot reject it). The flag in my opinion should be in a way that user can remove it from the library when they want it.
The idea can also be extended to a general labeling system so that users can label similar libraries with a uniform label.