6 clients use up 17!!cals

I've set up a windows 2 terminal server, with originally 10 cals. A licencing server is not yet installed since the 90 day grace period is still running. There are 6 ts clients (w95, 2xw98, wxp home, 2x w2k) and one nt4 server. Up to now only 5 clients could connect then the cals were used up, the licencing manager indicates that 13! licences were used up. After increasing the cals to 20 all clients can connect, however now 17 cals are used. Can someone explain this behabvior? Could it be that norton anti virus ce 7,6 uses 1 cal and when the terminal session is startet another cal ist used? How or where can i see which machine is using how many cals? Please help me, this problem is driving me up the wall.