The former Single Rider line at TSMM (in DHS) is now being used for doubles, parties of two who wish to roll the dice and maybe be seated faster than otherwise (and then again, maybe get shafted and take longer).
We're talking only about the split staircase at the very end of the standby line, after the merge with FastPass. The right-hand stairs used to be used for single riders, since a seat going to waste is a terrible thing (or so they say). That didn't sit well with guests, though, to have to share close quarters with strangers, so the idea has been dead for a few years.
The staircase is in use again, though, but now for parties of two. Why would they need parties of two? Because in theory there could be one row left in the eight normal lanes, but the next party in line is a party of four. In prior days, they would count back in the line until they found a party of two. Now they just grab for the double-rider line.
Sounds great, but it also sounds like a way to get shafted. The staircase is really the very last part of the line. The 'regular' wait here is not long. If there is any line of substance in the double-rider line, you could end up waiting longer. A lot longer. Making matters worse, when you have to choose which line, you are blind to how long the double-rider line actually is at the moment.
Perhaps because of the inherent unfairness, we watched the loader tonight take multiple people out of the double-rider line for no apparent reason (it wasn't to fill up the last row in the train; she loaded sets into rows 4, 5, and 6, and then asked the next 'normal' party how many they had). So this is very much a hit or miss thing, I suspect. I plan to not take any chances; I'll just stay in the regular line. Like I said, it's a short wait once you hit those stairs... unless you're in a nonmoving "special" line.