This only helps, if the other marketplace (or patreon or twitter or whatever) links to the exact same itch account.
They do impersonate the original creators.
So actually, if you see shiny new game on Steam and shiny new game on Itch ... that does not mean that the Itch version is safe, this means, there is a chance, that the itch account is faking it. Especially if you see a paid Steam game here for free... ;-)