I have seen that here and there, but why? Where does this second accent come from?
Are double consonants important to be pronounced differently than single ones in Greek? Would it often result in different meanings, like how in Italian penne and pene, or anno and ano, are not the same?
Double consonants (νν,λλ,μμ,κκ etc) don't sound different than (ν,λ,μ,κ).