I dno’t know what is the physical layout of your NSN bts.
– How many sectors in this bts ?
– How many antennas on the rooftop ?
– How many base stations (2G, 3G, 4G, how many operators, etc) are sharing those antennas ?
It looks like you are facing a mixed jumpers issue. This cell is sending its signal over two different sectors. Logically, another cell in this site should also face the same issue.
What you have to do is un-tangle the jumpers between the BTS and the antenna feeders. -or if no jumpers, just untangle the feeders)