The version number is an optional flag from butler. If someone doesn't provide it then we just show our database's unique ID for that build or file. For non-butler uploads it's just the file ID, otherwise the build ID.
I agree the number isn't helpful, one potential idea is to show the auto-incrementing number so it's not a very large number. We would only have this available for butler uploads though.
For regular file uploads, we currently don't let people provide a custom version, so we should make that available.