have reported about that problem long time ago
bug fixes/features request dm500
part of that problem comes when on one satelitte position presented more than one transponder with same TransponderID like:
12190L; 12226 L; 12380 L on 36E have same NID-TID(112-2)
http://www.lyngsat.com/36east.html
also i have similar problems with few transponders on 13E, but i didnt check why