Well Gemini and DD aren't exactly the same. Gemini is basically the same coaster with trains running side by side, but Dueling Dragons is totally different. It has 2 totally different coasters with different elements at different times.
This type of thing can be debated until Hell freezes over, and in the end it never mattered to begin with. I count some dual-track coasters as one coaster, others I count as two. Why? Doesn't matter why. You can count them however you want.
But on pg. 35 under "Kiddie, Dragon, Caterpillers, Miller, Molina, and Bradly Coasters", it specifically states that those only count as a half credit under the "kiddie coaster clone act of '74". I think that Veko kiddie coasters are up for addition on the next ammendment.
You can debate it and find interesting things to say about it, but the answer is so simple. You count racing/dueling/twin coasters as 2. Why? It may be the same ride and one structure etc., but it is 2 different coasters. If you have 2 identical spoons you don't call them one. Same with coasters. When the park asked for the coaster they said we don't want one we want 2.
Actually, the asnwer isso simple. Count them any way you want. As one or two, its up to you(hey, that rhymed!).
Coaster counting is only important to yourself and Paul Ruben. In the grand scheme of things, it dosen't matter. Everyone has their own way of doing it.
Though I've never ridden it, I count S:TE as a coaster, I count Racing coasters like Rebel Yell and Thunder Road and PKI's Racer as one coaster, but I'd count Gwazi or Lightning Racer as 2. But thats just me.
Basically, if RCDB has it listed, then its a coaster. The only time I differ from them is on Dueling Dragons, Gwazi, LR, Stampidia, and racing/dueling coasters where the layout is completely different. But, again, thats just me. I also count my 1 fairground coaster (my first Anton!) in the 91 coasters I've ridden.
LOL. As many times as this subject comes up, it's still so easy to get caught up in it...
My only point is, stripping anything down to the absolute basics reveals 2 coasters. If the "ride" or "attraction" needs both coasters to complete the experience, as is the case with Gemini or Racer, then surely it makes sense to call the whole thing one single "ride" or attraction", but not one coaster. Putting one title on the whole attraction makes the 2 coasters part of one entity of course, but they are still 2 different "coasters". If you were getting a material list together to build the 1 attraction "Gemini", how many coasters would you put on that list?