Why does Theseus think the young lovers have come to the wood in A Midsummer Night's Dream?

"These things seem small and indistinguishable, like far-off mountains turned into clouds." says Demetrius. Their memory of what has occurred seems vague. When you add that to the unlikeliness of what happened, it is easy to explain it as a dream.

But as Hippolyta says, "All the story of the night told over, and all their minds transfigured so together, more witnesseth than fancy's images, and grows to something of great constancy." In other Words, is it likely that all of the lovers would dream the same dream?