I had the same problem. It happens because in FFA mode CSDM logs 1 kill and 1 teamkill at the same time when you kill your teammate. In this situation top players become worse players and appear at the end of top players list. You need to turn off FFA mode in CSDM and install
this plugin (for properly logging FFA mode) and
this plugin (for infinite round). You must install both plugins - this will solve your problem. It tested by me and works fine