Yes, it happens quite often. Also I've seen double negation in American TV series, I've been told these are features of Southern American English.

hello, This is more of a slant on language or 'slang' (meaning a modified or transitory term.The vocabulary may not follow the appropriate or standard form of the language or to formal contexts. This can be dependant as to social status, cultural changes or distribution, and can be more playful than standard language), so it's not really wrong in my opinion

You are correct it should be I didn't kill anybody but in american programs they seem to use it a lot, just take it mean the same thing :)