I've noticed this before and have been puzzled by it. This afternoon, WWCR in Nashville, appears to be simultaneously broadcasting exactly the same content on both 9980 KHZ and 9990 KHZ. The references available to me indicate that 9980 KHZ is the frequency that the station can be expected to be found on at this time. Is the signal (although somewhat weaker but still very readable) on 9990 KHZ intentional, or is it some sort of unintentional "artifact"? If it is intentional; why would a broadcaster devote resources to transmitting the same content on frequencies located so close together?