How many times is the same file stored (deduplication)?

Maybe it is in the documentation, but I have not found an answer to my question:

When I do several restic backups with different tags, is a file stored more than once or does restic some kind of deduplication?

Example:

restic backup --tag local /local
restic backup --tag test /local/test

Addon question:
Are hardlinks stored as is or are the files stored multiple times, for every hardlink?

Example:

ln big_file1 big_file2
restic backup --tag big_files .

Inside the same repository, afaik tags does not matter for actual deduplication (they might only complicate parent-snapshot selection, which is fine) and similar data is deduplicated (with a few exceptions, but I’d consider these as corner cases).

For the hard links, I think this is the answer you’re looking for.