If these marks are
a bit worn out, I can not imagine a very worn out one.
However, the mark on the left could be the one of Zuan Piero Grappiglia, which is a mark that is quite often found on Venetian silver.

In the book of Donaver Dabbene is also mentioned another mark that has a similar bottom, and that could be attributed to several silversmiths.

It should however be said that in the book of Piero Pazzi which specifically addresses the Venetian silver this mark is not mentioned.
Best regards
Amena