Function to process duplicates of records

There are occurrences when a record is a duplicate of another record and it is needed to merge the two records. The app needs to be able to inform the user of a possible duplicate and offer to merge the records.

It would be good also to manually select records and merge them.

No files, tests, or entry points are named. Start by locating record handling in the React Native mobile app, then clarify how possible duplicates are identified, which fields survive a merge, and how manual selection should work. Done means users can be informed about possible duplicates and merge records either through that prompt or by selecting them manually.

Written by the indexing model from the issue text.