Both are Mdina, and both are late - late 1970s at the earliest I'd think, but more likely 1980s onwards. It's very, very hard to date them closer than that.
As regards signatures on Mdina...as I say in my book....not all early pieces (1969-72 and for a few years beyond) were signed. This was primarily due to the sheer amount of glass being made and shipped to distributors or otherwise sold. They just made so much it was more important to 'get it out there' and sell it than sign it. They only had limited numbers of staff and time. The lack of a signature does not indicate a second, as has been said above. The lack of a signature can even occur on later pieces, so the lack of a signature does not indicate an early piece. Always go by shape and colour here! The only instance concerning Michael Harris not liking to sign pieces relates to his name, 'Michael Harris', not the factory name, 'Mdina'.
Hoipe this clarifies things a bit!