dnd 5e – Does the Raven Queen replace Myrkul?

I'm confused about the relationship between Raven Queen and Myrkul. They sound like they have a very similar job description: they're both the ones you see when you die, and they both like to scare people about it.

Can there be two gods of the same domain? Maybe the Queen of the Raven takes dead elves and Myrkul takes dead human?

(This is specific for 5e)