passthru can't work when install two network card

hi All:
I meet a problem in my IM driver,when I install two network card,the system can’t start up.but if I only use one network card,it’s ok.
Why?
I have register two Timer in MiniportInitilize,if I install two network card,If it will call my MiniportInitilize twice?
Thinks!Waiting your reply.
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