Both pr. 23 and pr. 69 had similar type seccondary outfit, dual 152mm guns for anti-destroyer work and dual 100mm guns for AA work. Nothing wierd in it, Germany had similar outfit in the countenpory Bismarck and Shcarnost designs, as had Italian and Brittish BBs.
True, but it was quickly becoming obsolete. IIRC, only the older British boats had the single-purpose armament like the Nelson/Rodney; The KGVs had the excellent 5.25 inch DP guns as their main secondary armament. The Italians and Germans, frankly, were just plagued by some pretty backwards or outright weird thinking.
Though the Soviets tended to have a lot of Italian influence since that's why they let design their ships. The 100mm guns certainly would be big enough for the DP role, 152mm guns are legitimate cruiser guns.