bmi (British Midland) used to routinely board from door 2. When working those flights, Door 2 was preferred as it sped up boarding with the left right split and eased aisle congestion.

I remember a late Friday night in Dublin and all the ground staff wanted to get done work super quick, and so we disembarked and boarded through doors 1,2 and 4. I've never seen 195 people on and off an aircraft so quickly