Well I asked my uncle who is a Rabbi, regarding the halacha of repeating words. In theory there is no problem ever with repeating words as long as it doesn't change the meaning of the words. It is of course preferable not to and I'm not certain if while in the middle of a brocha you can do it. It is normal for words to be repeated by the congregants as well during "Aitz Chayim He" etc.
The problem is when they repeat words and go back to the beginging of the paragaraph for ex. and change the meaning. It is done by many Cantors but the less you do it the better.
