They are both "write in" because they did not receive the nomination of their respective parties. Because Cheek got enough signatures, his name is actually printed as a choice on the ballot as UNA (unaffiliated?) while Monks name, because he got some but not enough signatures, is
validated to be literally written into the blank space provided on the ballot (as opposed to someone writing in Donald Duck, etc.)
Sample Ballot (pdf file)
Nifong is part of a straight ticket vote. Most of the straight ticket votes are DEM unopposed. I would expect the Repubs to be paying enough attention to vote for the one REP candidate and then vote separately for DA. But will they just "check Cheek" (there's a campaign slogan) or remember to write down "M-O-N-K-S" and check that box.
Alternately, are the Dems who don't like Nifong (let's pray there are some) willing to separately check off the 5 DEM candidates in order to mark Cheek (I assume they won't vote for Monks).