I would say that your husband being simultaneously aware in the two data streams makes him doubly unusual. First that it happens spontaneously all of these years. Second that it does not interfere in participating in PMR as it has done with many who we now know, thanks to James Moffat, by either making them psychotic or leading to them being declared psychotic if they reveal their experience too publicly. It sounds like the difference is that your husband has this data stream available to observe but he is not participating with 'inhabitants' of NPMR, interacting with them or receiving some kind of directions or control. It is not intrusive within his normal PMR interactions and can be ignored sufficiently to allow normal participation in PMR.
PMR and NPMR are not always simultaneously present within our consciousness as Tom Campbell understands and describes Reality. And based on what you say above, your husband is not simultaneously in both of them but rather he simultaneously has access to the PMR data stream and simultaneously to a data stream providing him a display from the future probable data base. PMR, we would describe as a Virtual Reality, that our experience within it is provided to our core being, our IUOC, by a data stream generated by what Tom Campbell has called The Big Computer. It is our IUOC which then experiences that data stream which provides to it the experience of being you, the Avatar, experiencing yourself within PMR. These are very different things. This data steam to our IUOC IS
our consciousness, what we have available to be conscious of. Your husband has the additional data stream of the future probable data base available to be a part of his consciousness. It is AUM only as The One Consciousness that is fully conscious in the way that we think of ourselves as being conscious in PMR.
It is not my understanding that mediumship is the same as any of this. Rather it is an asking of their NPMR contact for information, which I understand to be normally received verbally within their mind and not observed like a 'face to face' conversation. Then they separate themselves and report normally in PMR to others or to record this information. Or alternatively if they are trance mediums, they can go into a trance and allow the NPMR contact to use their voice and body to communicate here in PMR. Again, I do not see either case as being like any of these other things we have been describing.
I could say more about how this kind of situation can occur in terms of a technical description. However I cannot explain every aspect of it like how can data about the past move towards the future to the present so we can be aware of it or how can the information about the future at some point be made available now at what is the now point for PMR. And the now point for NPMR is roughly, but not exactly, the now point for PMR. And now is not identical for all IUOCs participating in a VR. The information defining 'now' arrives at each IUOC participating in each VR at different times compared to the movement of time for the whole LCS. We can go into this if you wish, but it is also described in Tom Campbell's Model of Reality in his Wiki, specifically here: http://wiki.my-big-toe.com/The_MBT_Model_Link_Page