The Yale Doorman door lock uses Mifare Classic chips (NFC / HF) and writes to the chip at each unlocking, in a futile effort to secure the chip. So yes, it definitely exists. Check out this thread if you want details.
As for multi-use, well I now use my Mifare Classic implant to open my Yale Doorman lock (with its reading/writing funky sectors business), but my implant’s UID is also used to unlock my home computer under Linux, and my work computer under Windows. And I’ll soon try to find out if I can write a valid NDEF message beyond the Doorman’s working sectors to encode my site’s URL and have it read by a cellphone, without making the chip invalid for the Doorman.