Why when on shuffle and no repeat does my itunes replay certain songs?

This has been an issue for over a year now. Every time i chose shuffle on my itunes, any play list, and make sure there is no form of repeat, not one song over and over, not the play list as a whole over and over, does it play some songs more than once even if i just started the play list or closed out of itunes and entered back into it? For example, if i go into recently played i will look at the list of the 50 songs, none are listed twice but ill shuffle the play list and hear "lets go crazy" by prince twice in a 3 song span or "layla" by eric clapton twice in a row. The songs it does this to change and can play upwards of 3 times. If i hit next its like its shuffeling through just 5 songs rather than the 50 and when i check the "up next" none of those songs are showing to be repeated. Its super annoying. Anyone know? And of course when i show it to Apple it works like nothing is wrong.