I have come up with a very simple algorithm that permutes strings without repetition, and when I give it an input with repetition I get repeated permutations that I don't want.<BR><BR>For example ...

Ellin Kofsky Scholnick, Marilyn Jager Adams, Relationships between Language and Cognitive Skills: Passive-Voice Comprehension, Backward Repetition, and Matrix Permutation, Child Development, Vol. 44, ...