I've run across something similar to this before - I figure the drive hasn't refreshed properly, or something. Sometimes, when deleting files, unless they've been removed from the recycle bin, they still seem to take up space on the drive they came from.

I uninstalled the first installation and deleted the remaining files, as I did with the second. Probably just needs a good old refresh somehow (not the computer expert, do not intend on rebooting the computer at the moment after some of the problems it's had recently).