Here's what it looks like to me. When viewing comics only by a specific author, e.g. oneself, sort=score&o=1 puts the lowest-ranked comics at the top of the page, while sort=score&o=2 puts the lowest-ranked comics at the bottom of the page. However, if multiple comics have the same total number of points, then *both* sort orders put earlier comics (i.e. those with lower ID numbers) above later ones. This is why o=1 and o=2 might not look exactly the same. For example, as of just before I posted this, I have four recent comics with (I presume) 0 points. Those four will be the four at the top of my page when viewed in o=1, and the four at the bottom of my page when viewed in o=2, and in fact they'll be in the same order on both pages, i.e., chronological order.
As for whether the "score" link takes you to o=1 or o=2, I figure the PHP code just asks what "o" is currently set to, and then generates a link to the opposite. Therefore the explanation as to why you end up viewing the one you didn't expect probably has something to do with the path you took to get there.
I obviously don't have access to Johnny's code, so I could be wrong. But based on what I'm seeing, this is my guess.
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The what mentioned above is total fiction. Please don't take it seriously!