Not that I've seen. Probably the closest thing would be taking several similar JPEGs and putting them into an MJPEG movie. You could also use APNG or animated GIFs for a similar purpose.
I'm not sure how well that would work though, and it sounds like you're already talking about movie screencaps, so repacking them into a movie file sounds... counterproductive.
Maybe a better way, if you still have the clips that the screens came from, would be to simply find a command line tool that can extract the exact frame for you, copy that unique identifier into a text file someplace, and then you can always easily re-extract the frame when you need it.
97% compression for the JPGs seems unrealistic. The numbers in the comparison test you link to say the compression is about 20% – OneSolitaryNoob – 2015-05-28T05:30:01.377
@OneSolitaryNoob Did you forget that the JPEGs are similar? 110/111 = 99.1% expected compression. The comparison test that he linked is about compressing a single JPEG. – Navin – 2018-04-22T19:51:48.840
@Navin it's really unlikely. Even if they look nearly identical most of the pixels will be slightly different. – OneSolitaryNoob – 2018-04-22T19:55:20.033
@OneSolitaryNoob So what? 1 second of video (30 frames) can be compressed to about the same size as a single frame. As long as the slight difference makes up a small fraction of the data, you're all good. – Navin – 2018-04-23T01:57:28.233
@Navin thats lossy compression, many details are gone but most people won't notice. Paq* is lossless compression – OneSolitaryNoob – 2018-04-23T01:59:13.410