This is a small utility that copies matching tags from one git repository to another. And by "matching" I mean that there's a commit in the destination repository with the same SHA hash as the commit in the source repository that the tag points to.
git-copy-tags <source-repo> <dest-repo> [-f]
By default, the script is in "dry run" mode, which means that it only prints out what it would do, without actually doing it. If you are happy with the result, add -f.
After running the command with -f, make sure to run git push --tags in the destination repository!