Do follow you reasoning. The moment you switch to 28°E (port 4 of diseqc switch) the power is gone on the duo LNB (port 1 and 2). Somehow the switch in the Duo LNB still has to be switching or you would only have one satellite.
For this to work either both switches have to be of different modes (1.0 and 1.1) and receiving diseqc 1.0 and diseqc 1.1 commands for each satellite switch or the AZ box is issuing several same level commands: switch to 1, switch to 1, allowing both switches to switch?