Several of them.
Some of them closer to this reality than others.
At least one of them, if not several, are related to dreaming. Some of them are related to other planes of consciousness (and at least three of those are close to our reality, one of them so close that it needs to be empty of what can be thought of matter because it interfaces with our world - it is the reality I associate to OOBEs or 'astral projection', and others close enough to closely mimic a past/present/future of our reality where consciousness can be trapped in - hence ghosts). There is also, I believe, the "positive" reality - where black holes end up, a reality containing about 1.2 times the mass-energy of this one. These are the realities I am convinced exists.
Now - I also think that, theoretically, there may be three more realities: the negative entropy reality where the laws of thermodynamics work in a way opposite to this reality, and which might interface our reality at a so-called "point-zero" where, given the right circumstances, entropy can be traded (which results in a positive energy extraction for us, and a relief of pressure for the other), several empty sub-realities where it might be possible to travel, and the "master reality" which could be equalled to the Olympus or Heaven/Hell.
I have no idea how many there really are, though - but I know there's several.