I've seen them ask people to walk side by side in the line right before you go in but never in the house. The houses aren't built for that. You generally have to walk through pushing stuff out of your way that just wouldn't work side by side, not to mention the pathways just aren't really that wide.
I get what they're doing, no one likes waiting in long lines. There's a point though where it ruins the experience to the point that it's not worth waiting in even a short line. Personally I just completely ignore them. I look in the complete opposite direction and never make eye contact. The majority of the time if they're waving at me I just don't even see it. That being said I don't hang back and try to create gaps or anything I'm generally pretty much right behind the person in front of me, so what they're doing is meaningless anyway.