I finally got around to looking at the bounce of the garage door contacts with my scope. Found upon the first movement of the door a 100ms impulse that cuased the contascts to change state immediately. This was followed by another 2ooms of chatter before it finally got stable.
Since it appears that the SHN EZIO device does not debounce the inputs I debounced with an external RC circuit. Everything works just fine now. The EZIO device only reports one opening or closing.