po: Remove duplicate message definitions

This fixes fatal errors reported by msgfmt which made the build fail.

Note: The other translation of "Please re-enter this passphrase" uses
"das Passwort" instead of "die Passphrase". I chose to keep the
translation using "das Passwort" which seems to be the preferred
translation of "passphrase" used in almost all German strings.

Cherry picking translations is dangerous. Sorting messages by msgid
should make it less dangerous and would make it much easier to spot
duplicates.

• Fixes-commit: c54f7e154f1e1054af5b4819450d03aa05ad9106