This same problem exists in some CD players I've noticed. My car stereo is the worst. It has no concern for what track it has already played and will go back and play the same number about 3 times during a sequence. My Shanling player's idea of random is something like: 15, 3, 5,6,7,8,9,10,11, and then it freezes up and needs "rebooting". It's rather silly.
I'd be interested to know how exactly a random number generator is created in an electronic circuit. Perhaps this is something which is hard to create? Something must be amiss if the iPod can't properly shuffle 1400 numbers!