DeDup is an AviSynth plugin which finds duplicate frames in a video stream, produces a log file, and then removes them in a second pass. Unfortunately, it is limited to removing at most 20 duplicate frames at a time.
Some cheap keychain cameras produce broken video streams which end up looking like they have hundreds of duplicate frames. This is where DedupTrimmer comes in: after analyzing the video stream using DeDup, feed the log it produced to DedupTrimmer, and you will get an AviSynth file. This file contains a number of Trim commands constructed so that only the non-duplicate frames are kept.