I know that Russian silver is a very complicated matter and therefore I usually avoid buying it, but I always read the posts to learn something.
Today I saw on the internet this icon that the seller claims to be Russian from 1778, with 72 zolotnik fineness.

These are the hallmarks struck on the riza twice, ad abundantiam.

I do not have the knowledge to dispute these claims, but at skin this item seems to me to be phony as a six euro bill. Am I wrong?
I would be happy to have some opinion from experts in the matter.
Thanks for attention
Amena