MSNBC advertising

Has anyone who watches MSNBC ever notice how Headline News and Fox News advertise on MSNBC. Recently I saw an advertisement for HLN's "Morning Express" during MSNBC's popular show Countdown. Also, I hear Fair and Balance (not really), Fox News on MSNBC. Can someone tell me if MSNBC appears on CNN, HLN, or MSNBC? I think its really odd how other networks advertise on MSNBC