[lambda_obrien]

If they're almost the same, could you use one git repo with different branches for each version? Or archive them with restic into a folder and restore which one you need each time. Either method should deduplicate data if they're mostly the same file structure and content.

Edit: You could even have several read only shadow copies of the repo for parallel working directory usage, if your hard link the .git directory except for the HEAD ref in each.