How do you have the wiring ran from the doorbells to the channelvision? Do both doorbells work one at a time? If so, how do you have them wired together, are they both ran directly to the channel vision? If I recall this unit does not have 2 separate inputs for 2 separate doorbells, are they connected to the strike connections on the channel vision? Are you sure you have them both connected to the doorbell and not one to the striker?