2 clines??? But both lines would run from the same source so if one line when down I would expect the other line to do the same, seems odd to me to give 2 lines for 1 box from the same provider. I know of poeple who run 2 lines on 1 box but each line is from a different supplier so if 1 line stops the other will just start and viewing will continue.
As for cline v nline, its better to get a nline but if the cline runs stable on your box then a cline will do just fine. Cline come from a CCcam server and nlines come from a MGcam server and Mgcam is the newer of the 2