This happens all of the time even with video that was both shot at the same tape speed. If the video cams are not running off of the same timecode generator, then this can happen. I don't really think what you are experiencing has anything to do with LP vs. SP at all really as it would be just as likely to occur if they were recorded at the same speed. You need to sync the heads (near the beginning) and then you need to stretch/compress one of the videos near the end such that the tail becomes synced as well. The stretching/compressing algorithm should handle any pitch-shifting if needed, but usually we are only talking about a very small time difference so pitch should be alright. Different apps require different methods, but the concept is the same, sync the beginning by SLIDING one video, then sync the ending by compressing/stretching one video such that the ends are in sync. It can be a PITA, but it works.