Hmm, kinda late for me jumping in now, but what the hey. I'll throw in my $.02.
For me, the two tracks must feature something significantly different about them, not just be mirror clones, or VERY close to it.
Some rides I count as one: Gemini, all the Paramount Racers, Space Mountain WDW, KW Racer (how *could* you count it as two?), Colossus.
Some rides I count as two are: Windjammer (yellow was different enough for me to warrant the double count), Dueling Dragons, Gwazi, Lighting Racer (originally counted this as one, but changed my mind :)), American Eagle (strong preference for red side, as it features twice as many hills than blue), Twisted Sisters, Chiller, Rolling Thunder SFGAd, etc.
So that's my stance. If the coaster track has enough different to it that it feels noticeably better/worse, I count it as two.
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"Yes if by crestfallen you mean KILL US!" -- Homer J. Simpson