Hi Alpha
No this had not occured to me. I have 8 Franchini items including two other unmounted glass plaques, one seal and five bottles, three of which have silver lids with the same design filigree work as my box.
I believe they are all genuine and dated correctly. I have collected them from eight different sources over the last twenty years.
If you would like further info on the items I would be pleased to help.
I also have thirty or so Venetian bottles with faces from the 1880 period.
Roy