Do beer blends exist? I asked a bartender what she was drinking near the end of her shift. She said a blend. Of Bear Republic's Racer 5 IPA and North Coast's Le Merle (a Belgian Saison).

I tried it and it was great. I already liked Le Merle except it had a bit too much of the Belgian kick, and I never liked Racer 5 at all, but together somehow the attributes I didn't like canceled out or masked one another.

At the risk of heresy, I wonder if mixing beers is or was ever a (semi-)official thing anywhere. I've heard wine blends mostly exist as a product of leftover grapes, so their justification doesn't apply to beer. Still, if the taste is great, why not have beer blends? With the distinct taste variations of hops alone, I wouldn't be surprised if great combinations could be found.

So, to put succinctly: Are beer blends being served anywhere?
There are beer blends served in England and Scotland although it tends to be the older drinkers.

Mild and Bitter is one where a half pint of bitter is mixed with a half of mild.

Brown and Bitter is half of bitter with a brown ale such as Mann's.

A common Scottish blend is the Black and Tan which is Guinness and IPA/Heavy - this can also be made a Sweet Black and Tan by using sweet stout and IPA.

Before Fullers shut Gales of Horndean down they produced a bottled Christmas ale which was a mix of their HSB premium bitter and their 555 mild with spice.