Hashcat to clean a wordlist

[Dinarius]

I read in a two-year-old post that Hashcat can identify doubles of letters. I have a very basic word list I'm toying with of just 4K words, each four letters. I have no hash to throw it at, but would like HC to see the list of valid words, and output a file of those words/attempts MINUS any words where any letter is repeated. "NODE" is written, "NOON" is not.

Also, my words are only separated by spaces. Can the separator character be defined going IN or do I need to replace spaces with carriage returns (I'm not sure how to do that)?