For a Records Library Versioning Settings, we had the "Create major versions" turned on, but the versioning was still adding an underscore and random characters to the end of the file name.
To fix this issue, we had to go back into the Content Organizer feature and make sure "Use SharePoint Versioning" was set in the "Duplicate Submissions" area.
1. Go to Site Settings / Content Organizer: Settings
2. Go down to the "Duplicate Submissions" area
3. Check "Use SharePoint versioning"
If you don't see the changes >> i.e. the versioning take affect and only show a single file name, and version history is only seen via the edit sub-menu, make sure the Central Admin Content Organizer Processing timer is set to what you need via:
Central Administration --> Monitoring --> Review job definitions --> Content Organizer Processing