How someone is pronouncing W is actually a good way to guess where the speaker is from, or where the person that taurht them learned english.

double you for british/american accents

dubba you for some american accents

Dablu or dabloo is a clear indication that the speaker is not a naitive western english speaker, usually indicating indian for the speaker.

double v (often pronounced as double we) usually points towards somewhere near germany/holland/belgium

I’ve never heard anyone say just dub, curious if anyone has?

Edit: I lied. W pronounced ‘dub’ is only ever used to indicate a ‘win’. e.g. ‘Took the dub’