The media-video/{mjpegtools,mjpeg-tools} ebuilds seem to be similar but not quite the same. They both install the same things, but different versions apparently. Anyway, one should go, and it's unclear to me which at first sight.
Hi! Took a look at them. The mjpegtools are the most current version and the name without the "-" matches the package tarball. So unless there are any objections, I'm going to hose the media-video/mjpeg-tools. As a side note, all these ebuilds are a little stale and need at minimum a syntax update.