Apparently these particular files aren't yet a staple on Limewire because I've left my computer running 4 days straight and the same 4 files have been 9/10 of the upload slots. Yesterday I decided to pay attention to the ip address part of the monitor function, and frequently have found the same ip addresses occupying more than one slot downloading the same file. One person was even occupying 4 slots for the same file (upload @ same %).
At first I thought it was just the actions of someone overanxious to get the file. Considering that the queue for these same files was also full, I deleted the redundant uploads, leaving the ip address with one upload per file (freeing slots for those on queue). Then I noticed this happening with more than one person. I've frequently come back to visit my computer to find that many uploaders have more than one upload of the same file going on.
Is this some sort of software quirk, or is it just people trying to increase their chances of getting a file (not that this works any better, considering that the file is from the same source. Or can't they tell this from the available files list?)