I highly doubt GitHub maintains two copies of the same object (not counting replication). They likely copy most of the repo metadata for forks, but if two objec

I highly doubt GitHub maintains two copies of the same object (not counting replication). They likely copy most of the repo metadata for forks, but if two objects have the same SHA, even in completely different repos that were never even forks of each other, they can just store one copy. You can see evidence of this if you look at some of their advice for how to remove all traces of some data (say, you accidentally checked in sensitive info to a public repo and now need to make it totally inaccessible)