Yes, but if you think about it, while both engines are operating on a twin, it's really no different from a similarly complex single. What's the difference between an Islander and a C182? The BN2 is slower and has two of everything, it doesn't require any extra skill to move two sets of levers and look at two sets of engine instruments. So going by your logic, all twin time should be logged as SE time unless you're actually assymetric.