As I continue my quest to make sure I understand rclone's behaviors, I have been playing with
--track-renames-strategy modtime (since I will be syncing to an encrypted remote). I noticed in testing that in the face of ambiguity (more than one file with the same size and modtime), rclone will pick one (the first?).
Personally, in the face of ambiguity, I would prefer that rclone just decide it can't track that rename and do a new transfer + delete. It will alleviate some of the unsafeness of this strategy.
Would it be possible to add a flag to do that? Actually, I would say the default should be to not pick one and instead print a warning and then not track that rename.
(If spent some time analyzing my files and found that I had a lot of files with the exact size and modtime. Turns out they were from a macOS sparsediskbundle. Some common operations on them set all bands to the same modtime and by construction, all bands have the same size. Furthermore, it can get really nasty if they get messed up).