I would interpret 'logging as a single entry' as adding the block times together, without the interval. AMC1 FCL.050 requires you to log 'total time of flight', and this still applies:
(g)Flight time is recorded: (1)for aeroplanes, touring motor gliders and powered-lift aircraft, from the moment an aircraft first moves to taking off until the moment it finally comes to rest at the end of the flight;
As for logging different classes or registrations as one entry, I see that the explanation states that you should log 'SE or ME'. That prevents you from logging both in one entry in my view. I can't find a similar restriction on type/class but why make things difficult for yourself?