Probobly "broken" for a long time in my opinion. I would be interested in knowing what reasonable purpose there is to have the camera switch active cards when the power is off. I can understand if you do it when the power is switched on but OFF should be OFF!
Cool but more chance for dust and dirt to enter the camera. It's a good short term solution until it gets properly fixed.
What makes you think it's 'broken'? AFAIK, it's been that way on all the 1-series bodies which have dual slots - I rather think it's that way by intentional design, not error.