Mintmasters come and go, minters and their equipment stay on. I think the real difference is that the mint is privatised. It is not unusual for tenders to specify that only state-owned mints need apply. However, it is difficult to see the connection between that and the added lion. If I'd have to guess, I'd look at the insecurity of the ruling family of one of the smallest European states, as illuminated before by their unwillingness to have coins - even joint commemoratives - without a portrait or cypher of the grand duke.
Peter