They (SD2) all have 2 slots, the second isn't used in the non commercial version and is covered with a manufacturer installed tape. I haven't looked at that area on the "+" version but I suspect it's the same.
You can see both in this picture.
When we were testing these the second sd slot was was populated with an card used to store flight data on the non-enterprise drones. I"ve not heard of the second card slot being used for anything else on the consumer version though.