KJNB-LD (RF 27, Virtual 39) and KJNE-LD (RF 22, Virtual 42) are seperate low power signals transmitting from different tower sites to cover more of the Jonesboro DMA:
You may be able to receive both where you are, but there are areas that only get decent reception of one of them.
Network buyouts are never going to happen in a market this small, Jonesboro is ranked 183 out of 210. Plus you don't have enough full power stations like larger markets, so CBS and Fox are stuck on LP signals, while your CW and NBC are subchannels on your ABC station. Networks prefer major and large markets for their O&O's, the few smaller markets that have an O&O are usually quirks related to past mergers. (i.e. The 55th ranked Fresno having an ABC O&O because of the CapCities/ABC merger)
Memphis on the otherhand is ranked 51st, has enough full power stations for the Big 5, Ion, TBN, a local Memphis PBS, a cross-border Mississippi Public Broadcasting station, local religious stations, and a bunch of Class A and LPTV stations affiliated with other networks like MyNetworkTV, Azteca, Daystar, 3ABN and other diginets. At one point their Fox was an O&O, but back in 2014 Fox traded it and Boston's Fox station to Cox to get an O&O station in the San Francisco market since it's also home to a NFC team.