Authors can upload multiple versions of the same file.

This is a feature request in my book
It's basically 'add filehash module to core'

IMHO it makes a lot of sense from developers, site builders and editors perspective.

I suggest this should be a constraint (e.g. data validator) that could be activated per File field instance.

I think that the JavaScript could likely be done with something like https://stackoverflow.com/questions/1655769/fastest-md5-implementation-i... but there are probably better ways to do this.

It is also interesting to think about the CO2 costs of loading extra JS and weight that against the occasions where someone uploads a file. I don't know how to balance that score out, but it is something to think about.

Much easier to think about adding a library to do the md5 hash on the backend I assume. It would only be executed when needed.