remove duplicate matches. see description

so first i removed the 0.5% error duplicates, and that was working fine. and then i implemented the algorithm you posted, and it looks like i'm doing something wrong with the math.. i was testing the A5 images, not all the matches aren't showing up because they're being considered dupes. i've been staring at this for too long and can't figure much out right now.. i'll take a look at it again in the morning but if you have time to take a gander, feel free