A card will respond only to its own address, and each card must respond to a different address. Two cards can't use the same address.
Interrupts are a little more complicated.
When you select a URL with your browser, the Web site is contacted and data begins coming in to your modem. This is an interrupt. There are several, and their assignments must be known. When an interrupt comes in from the modem you would not want to go check the mouse instead. Not only does this make the process automatic, but it means that conflicts can be avoided.