Git stores files internally using the Hash of the file contents. This means that files with identical contents will only be stored internally once and each file that has these contents will point the to same 'blob'. This is a by product of Git using Hashes for storage and results in some space savings when this occurs.
In this video using the VisualGit tool (https://visualgit.net) we examine the internals of Git as we setup a scenario to demonstrate the above