I have two TIVO HDs one the more advanced. I have single stream cable cards, two in each. I want to replace them with two multi stream cards, one in each. I have read where sometimes it works and other times it does not. i am trying to reduce my bill as I am being charged for three cards now. Is there a trick to making on multi stream card work in each unit? Also, I am in Delaware and they tell me I can't go pick up the cards but needed to set up an appointment for next week. Thanks in advance for your help.