how to block c-line for 2 different servers?

hi, I have a question, for example I have 2 different servers, server1 has and server2 have got different cards and caids, but they have same cards too, server1 has an efficient Sky card for example, but server2 has same card too and it freezes, but usually server2 tries to decrypt the channel, how can we block server2 in oscam configuration? thanks for your answer