My bad. It seems there is a "Add as new translation" icon and shortcut in SDL Trados.
Select this to update the translation memory with a new (duplicate) translation.
You must perform this action prior to confirming the translation otherwise it will automatically edit the existing translation when it is confirmed instead of adding the translation as new.
I rather meant whether Trados has its own similar concept of Alternative Translations.
If Alternative translations aren't saved in the Finalized translations, it will be difficult to check whether SDL Trados supports AT.
CafeTran feature of Alternative translations works for the current session only in Studio project. By the way, I wonder if that CAT tool support the AT concept (apart from segment versioning).
Is this still true for Trados and other external projects?
If so, at least now removing alternative translations can be done quickly via Task > Remove alternative translations.