There may be one reality.
But each individual/sentient being/consciousness that is viewing/experiencing/observing/participating in the "reality" event has a set of subjective and unique perceptual filters through which the "reality" percolates, on it's way to "full" perception. These filters are based on your available bodily senses, and your beliefs.
For example if you believe time does not exist (that the past is a memory and the future does not exist) that there is simply "the present", then in that case your perceptions of "reality" will be very different from another who strongly believes in linear space-time.
There is also strong evidence that everything influences everything else, meaning that if you are present you are influencing the "reality" that others perceive.
Heisenberg Uncertainty Principle
http://www.aip.org/history/heisenberg/p08c.htm
"I believe that the existence of the classical "path" can be pregnantly formulated as follows: The "path" comes into existence only when we observe it."
--Heisenberg, in uncertainty principle paper, 1927
From the web page:
"
Heisenberg also drew profound implications for the concept of causality, or the determinacy of future events. Schrödinger had earlier attempted to offer an interpretation of his formalism in which the electron waves represent the density of charge of the electron in the orbit around the nucleus. Max Born, however, showed that the "wave function" of Schrödinger's equation does not represent the density of charge or matter. It describes only the probability of finding the electron at a certain point. In other words, quantum mechanics cannot give exact results,
but only the probabilities for the occurrence of a variety of possible results."
Imagine that.