A mockup for this feature can be found here.
The team from JabRef commented on the mockup:
Synchronize conflict resolution: Please look for the "Merge Entries Dialog". Refs #6021. https://docs.jabref.org/finding-sorting-and-cleaning-entries/mergeentries. You can just call it. Refs #5688.
The functionality for solving BibTeX conflicts needs to be implemented, and given the comments from JabRef, it seems that it should be quite easy to utilize the function specified in their comment above.
Related issues: #4 #16