With different transliteration that one at least makes sense. Nikolay = Kolya. But one that'll send most non-Russian speakers for a loop is Alexander = Sasha. It's like Richard = Dick, though there there's at least a rule that makes that one make sense (a rhyme with a shortened name so Richard -> Rick -> Dick, William -> Will -> Bill, etc). I wonder why it didn't just end up as Lexa, which would fit the other patterns for Russian names/diminutives.

And then we add the diminutives like Kolichka. Though, admittedly, there's much more of a pattern there.

Russian diminutives, making nicknames much harder to track for those not familiar with the culture and language. Vladimir is Vova is Volodya, same person. Then other parts of their full name may have variations depending on use.