Why would one choose to accumulate old AutoSave files?
By default, when you open an SKP file the 5-minute Auto-Save clock starts.
At the 5-minute mark SU creates an AutoSave_File Name.skp file of the active model in its current state.
At the next 5-minute mark, SU creates a new AutoSave_File Name.skp file of the active model in its current state, overwriting the existing AutoSave_File Name.skp file.
And so on, every five minutes.
Any time you save the active model file the AutoSave_File Name.skp file is deleted; the 5-minute Auto-Save clock starts and at the 5-minute mark, SU creates a new AutoSave_File Name.skp file of the active model in its current state.
When you save and close the active model, the AutoSave_File Name.skp is automatically deleted.
The only time the AutoSave_File Name.skp file is permanently saved to disc is when SU exits abnormally.
That is, when it crashes.
All the above is to illustrate that, after a crash, if you find an AutoSave_File Name.skp file, it would be the most current version of the model.
Open the AutoSave file and have a look.
If it’s OK, then…
File > Save As … Give it the original file name to overwrite the existing original.
File > Save As … Give it the original file name appended, say, with _001 to preserve the existing original.
Either way, the AutoSave file is no longer needed.
Go back to the folder and tidy up; delete the now redundant AutoSave file.
Setting File Recovery Preferences — SketchUp Help