This appears to be an issue with the Ultimate Guitar app and the way it names files that are generated for sharing content. UG support representatives are aware of the issue and have stated that their development team is looking into the matter.
Essentially the UG app generated temporary filenames and cycles through these names. If you use the Copy to OnSong icon that appears within the Ultimate Guitar app, this file is transferred to OnSong. OnSong uses filenames to identify existing songs in your library. Once a duplicate filename is used to generate content, OnSong will prompt you to Update, Duplicate, or Skip the file. Much of the time users tap "Update" out of habit and this will overwrite the existing song in your library.
There are two ways to work around this issue.
- When presented with a screen to either Update, Duplicate, or Skip importing the files, choose Duplicate. This will ensure that a new song is added to your library each time.
- You can also use the Add To OnSong action to import content. To do this, tap on the "Edit Actions..." link at the bottom of the share menu (iOS/iPadOS 13 and higher) or tap on the "More..." icon in the row of greyscale icons (iOS 12 and earlier) to enable the Add To OnSong action. You can then tap on this action to queue the content for import into OnSong without encountering the file naming problem.
Also, please be aware that OnSong versions 2020.0 and up released and changes how the Update, Duplicate and Skip screen appears. The Update option now appears as a destructive option in red and also prompts you again about overwriting content in your library to ensure that you don't overwrite existing songs.