I've made several outputs for sound turnvover and VFX turnover. Reference files, I am making then directly from Avid to mp4 and using the timecode burn-in filter.
I keep getting movies with duplicate frames. It will double up a frame 1 to 4 times in a 20 minute reel. Usually at a 15 frame. The movie will have two identical frames at say 1:13:32:15, throwing off the length of the reference.