I'll give an example. Today I attended a funeral, for the mother of a friend of ours.
As I sat in the room, I felt an intense personal experience. This was uniquely personal to me - my thoughts and visions, were all uniquely mine. No one else in that room was having that experience except me. All around me, everyone else was also having their own unique personal experience, and I could see it was different for everyone. So much passed through my feelings and thoughts, that I could never explain it, or even attempt to describe it effectively.
But I could also step outside my personal experience, and see what was happening in objective reality around me. What I saw was death touching everyone in the room, and through that, everyone had a window of awareness opened to the vast bedrock of the sadness of life. That seeing I can bring here and describe, and I'd wager every seer here has seen the same thing at a funeral. That seeing is open to validation by other seers.
And yet, another seer here could say, what she saw at funerals, was not everyone being touched by death, but everyone being touched by their own double. I would have to agree. Once that view was said to me, I also can say I saw the same thing. Then another seer may say what they saw was the coffin transformed into a vast chasm revealing a vista of infinity, and everyone present standing along the crest of the precipice, gazing out into that endlessness. I would then say yes, I saw the same, now you mention it - I can validate that. Then another seer might come forth and say he didn't see everyone being touched by their doubles, but everyone being touched by one double - the face of infinity itself. And I would also agree. Then another seer at the same funeral might say, what they saw was the spirit of the departed one, wandering around amongst the crowd. Yes, I'd say, I also saw that.
These things are verifiable by others, and yet for each seer, their personal experience would be unique and not shared. Nonetheless, that does not mean that there are not times when personal experiences are shared. Some events can be so powerful, and some people so powerful, that everyone present has exactly the same personal experience. It is said that Atisha in old Tibet had this power, to allow everyone to experience the same. Another example is the sorcerers of old, who united their personal visions to create another world into which they all transferred. It could be said that that process is precisely why we all see the same thing during our waking hours - we are sharing a non-unique personal experience which we call the 'world'.