I don't think this is actually fully true.
They are both competing for the midfield spots, yes, but when you look at the kind of players they are, I'd say it's more like:
Davies/Gana
and one of
Schneiderlin/Gomes
Davies replaced Schneiderlin because of necessity. I'm pretty sure if Gomes was fit, he'd be the player replacing Schneiderlin.
That being said, all of our midfielders need to be capable of getting on the ball at times, but it's fair to say that Davies and Schneiderlin aren't exactly the same types of player.