i've seen this once before, despite empegs insistance that the playlist random stuff is 100% correct i'm sure there's a problem somewhere, I had this when I'd randomised a playlist (my entire collection which contains only full albums and each album only once) and I had the usual bizareness of tracks from the same albums being very close in proximity to each other - but I also came across say a block of 10 tracks which were duplicated (from different albums - different arists), so like ABCDDEEFFGGHIJKKLLMMNN etc..
...I rerandomized and it went away...
Adrian