Every link you create in Bitly is unique and tied to a specific long URL, so there can only be one version of a link. For this reason, links can't be reused (though they can be redirected).
Once a back-half is used, it can't be used again with that same domain. You can use the same back-half in multiple groups as long as you use a different domain. This is the case whether the original link uses your custom domain or bit.ly.
While you can't use the exact same link, you can use the same terms in different links in a couple of ways. For example, if you want to use yourdomain.com/sample but that link has already been used, you have a few options:
- Change the capitalization: yourdomain.com/Sample
- Add characters: yourdomain.com/sample2022
- Use a different back-half: yourdomain.com/sample-sale
If you have multiple custom domains, the same back-half can be used in multiple groups, provided that you use a different domain.