I recently heard the word pre-prepared, and not being a word historian, I don’t know whether this is an old word that’s being used again or a new word needed to meet the demands of our fast-paced society. (Please note the sarcasm.)
I’m guessing that it’s the latter–that somehow someone has decided that since some things, such as food, have two levels of preparation, we can call the first layer pre-preparing, as in How to Pre-Prepare Foods for Weight Loss. (By the way, the headline makes it seem as if it’s the food, not the person, who’s is being prepared, I mean pre-prepared, for weight loss–I guess when the food is eaten, it will weigh less.)
Prepare means to get something ready in advance, so pre-prepare must mean to get something ready before you get it ready in advance.
I’m not ready to be that prepared.
–Paul
Everything Language and Grammar 
It’s the result of excessive preoccupation with being accurate and not being satisfied with reliance on the reader’s commonsense. It’s akin to saying ‘I non-concur’ when others around the table say ‘I concur’. Indeed, the phrase ‘I disagree’ or ‘I beg to differ’ or some such are considered aggressive dissension. Hence, it’s true, that’s how they talk at Pentagon, the phrase ‘I non-concur’. Pre-prepare does seem a bit excess-excessive, even by official standards. Cheers!