MarsSeed [1] filed a request to merge mdbtools-beta [2] into mdbtools [3]: Upstream doesn't release betas (or anything else for that matter) since 2021.
So I think it's better to keep only the stable package, but not the beta one, which has been a duplicate of the former since Sep 2021. [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/mdbtools-beta/ [3] https://aur.archlinux.org/pkgbase/mdbtools/
