I am trying to render an edited clip at 23.98 fps for use with motion tracking in a different project that shares the same frame rate. However, when I go to the tracker when the rendered clip is loaded, some of the frames show up twice in a row, thus throwing off the whole track. Any idea why this is happening?
Most likely the video is recorded using a LongGOP format and not an intraframe codec.
What that means is that every frame does not contain the full information for the picture, but only records the changes from a reference (I) frame. Blende has a hard time dealing with that format.
Try exporting the video as an image sequence or a video format with intraframe encoding, so that every frame is available to blender for tracking.