I don't know how to store multiple images per track, or if it is possible, but it raises the challenge of working around MC's Album-oriented approach to images -- made clear by the term Cover Art, rather than Track Art.
My wish is that the Cover Art lookup system would allow some options to better control Album art, and also Track art. Perhaps others will jump in with improvements or corrections to my understanding of how it now works and might be improved.
Right now Cover Art lookup either finds nothing, or it finds what is already on the local drive that matches the album track (presumably by album name + artist name), then it finds the same on the Internet, and if there are multiple choices it allows choosing one. That's a big help, but it doesn't handle all the situations I regularly encounter.
Wish #1: Allow choosing NONE, so in the Cover Art dialog it's possible to skip image choices that are simply wrong. This might be combined with the ability to delete a totally wrong image from the album and/or file system. The workaround is to let MC use an image, make a note of the track, then later go to that track and Remove the cover art image.
Wish #2 is for the Cover Art lookup, whether showing some "found" images or not for an Album, to also allow browsing the local drive in case there's already a better image that it didn't find. This would almost always be the case if there's an artist image that isn't named per some Album title. The workaround is to do this later and manually update selected tracks. But see "Challenge" below.
Wish #3, perhaps an alternative to #2, is for the Cover Art lookup to allow pasting in of an image from the clipboard, so when it doesn't find a desirable image through its automated search, the user can jump to a file manager or web browser, locate an image, return to the Cover Art dialog, and ADD that image on the spot. Again the workaround is to go to the track later and do this.
CHALLENGE: MC's Cover Art behavior, even when updating tracks manually, creates a challenge where the user isn't happy to assign the same image to all tracks of a given Album. What's missing is some way to specify that a given track's image is NOT associated with the Album name. This would allow any Album track to receive and retain an arbitrary image, such as an artist photo. Right now if the image is changed for one track of an Album, instantly ALL the tracks of that Album get changed to that image because it is assumed to be the Album's image, not the track's image. That's probably desirable in many cases, but certainly not all. It can be rather horrifying to see the prior image disappear from tracks that were not intentionally being changed. It can be quite difficult to find and restore the deleted image. There's no obvious way to prevent this other than to delete the track's Album name before changing its image, rather drastic.