Region names are initially derived from either:
These are not audio files, but regions that represent the full extent of an audio file. Every time a new recording is done, or a new file is imported to the session, a new region is created that represents the entire audio file. This region will have the name of the track/playlist/original file, followed by a "-", then a number plus a dot and then a number.
For recorded regions, the number will increase each time a new recording is made. So, for example, if there is a track called Didgeridoo, the first recorded whole file region for that playlist will be called Digderidoo-1. The next one will be Digeridoo-2 and so on.
For imported regions, the region name will be based on the original file name, but with any final suffix (e.g. ".wav" or ".aiff") removed.
Normally, whole file regions are not inserted into tracks or playlists, but regions derived from them are. The whole-file versions live in the Editor's region list where they act as an organizing mechanism for regions that are derived from them.
When a region is inserted into a track and playlist, its initial name will end in a version number, such as .1. For a recorded region, if the whole file region was Hang drum-1, then the region in the track will appear with the name Hang drum-1.1. For an imported region, if the whole file region was Bach:Invention3, then the region in the track will appear with the name Bach:Invention3.1.
Duplicating or splitting a region creates new region(s) that are based on the same original files. Hence, they share the same base name (in the example above, Hang drum-1), but their version number will be incremented each time. Duplicating Hang drum-1.4 by left dragging it will create a new region called Hang drum-1.5. Splitting Hang drum-1.5 by hitting the S key will remove the Hang drum-1.5 region and create two shorter regions named Hang drum-1.6 and Hang drum-1.7.
Regions can be renamed at any time using the region context menu : right click > name_of_the_region > Rename... . The new name does not need to have a version number in it (in fact, it probably should not). Ardour will add a version number in the future if needed (e.g. if the region is copied or sliced).