This topic comes up every once in awhile, and holy wars have been started over it. ;) My personal feeling is that if it has two circuits that do their own thing (like Dueling Dragons), it's two coasters. I would personally (and have) counted Racer as one.
Still, the track record function doesn't care how many times you enter a coaster in to your track record, so if you think it's two, simply add it twice.
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Jeff
Webmaster/Admin - CoasterBuzz.com