When records are merged, there is not a way to undo the merge without restoring to a backup of the database. This solution describes the best practice for making the records separate again.
If two records are inadvertently merged, decide which record should be the one that already exists and which one needs to be created.(BB367934) It is recommended that the record with the most information be the record that is currently in the database. This way, less time is spent creating the new record. Users can add an annotation (BB126716) to help distinguish the records in the future.