Pistols with snakes

[corrado26]

Due to the Corona crises there is enough time to spend it with my collection instead of making visits and I found a pair of pistols with since a long time unanswered questions.
The first question is where and/or for which country these pistols have been made, were they made in Italy (Brescia/Naples) or in rhe Osmanic Empire or perhaps in Russia? The second question is the meaning of the thumplates with the snakes. The pistols have a total lenght of 490 mm and the mounts are made from silvered brass.