Can you tell the difference in the accents of someone from Murmansk and someone from Arkhangelsk?
I have left my home city Penza for Moscow. Absolutely no difference.
There are many people in Moscow from many places of Russia. No difference.
A.e. at my workplace there are people from Samara, Penza, Moscow, Novosibirsk, Yekaterinburg, Omsk and other cities. Absolutely no difference.
I think in most large Russian cities there is no difference at all.