Mondas is the Earth of the Creation story, made by God and populated with Adam and Eve, the Garden of Eden, the Snake, the whole big blue marble.
Meanwhile, Earth Prime-Time, "mostly harmless" and most similar to our own Earth, was built as a super computer by the Magratheans. Its version of Adam and Eve were astronauts Adam Cooke and Eve Norta, both from other worlds. In fact, it's our contention that Eve Norta escaped from the much older civilizations of Mondas. The "star chart" she drew in the dirt in explanation to Cooke seems to tell the story of Mondas. (As Cooke interpreted it: "That's your planet; that's where you came from. Your planet got out of its orbit and moved away from your sun. That's where you went; that's where your world went. But you got out.......") This means Mondas had developed interplanetary travel by the time that the Dawn of Mankind was beginning on Earth.
Being the much older planet, the evolution and civilization of Mondas developed earlier and perhaps even quicker than that on Earth. For one thing, they probably didn't have a Dark Ages which impeded scientific advancement on Earth. That gave Mondas a huge boost in their development.
In the week before 'Game Of Thrones' premiered, 'Chuck' Bartowski nearly sabotaged it all with a Zonk......
'Tis a Zonk most easily splained away, my Lords and Ladies!
This scenario would be more likely - surely there must have been pockets of resistance on Mondas against the transformation of the planet's humans into the Cybermen, even to the very end of the planet's existence. One of those last humans, like Eve Norta before them, may have escaped the planet by rocket-ship as it approached the Sol system in the mid-1980's, bringing with him (or her) tales of the realms in Westeros long ago. This time, the Mondasian ship crashed in a location accessible to the televersion of George R.R. Martin, or the Mondasian human may have actively sought out someone of Martin's talent to tell the tale of Mondas, to keep its heritage alive.
This could also have all been done automatically, like the Kataanian beacon seen in the "Inner Light" episode of 'Star Trek: The Next Generation'. In fact, a Mondasian beacon (perhaps based on technology stolen from the Kataanians while Mondas traveled the universe) may have made contact with the minds of several likely candidates, so that many aspects of Mondasian culture could be kept alive; Martin only received the information about the realms of Westeros during the Mondasian Middle Ages.
So that's good enough for the book series; but what about any future Zonks that might mention the TV series? (And my prediction is that it will be 'The Big Bang Theory' that does it first.) If it happens, then we let Toobworld follow the real world's lead - that somebody decided the books were good enough to develop a TV series about them. And if any scenes from the actual series are shown on Toobworld TV sets, then we'll just say that the actors hired bore incredible likenesses to the "real" people who lived in Westeros on the planet Mondas a very long time ago.......
'Game Of Thrones'
'Chuck' - "Chuck vs. The Family Volkoff"
'Wizards And Warriors'
'Legend Of The Seeker'
'Doctor Who' - "The Power Of The Daleks" & "The Tenth Planet"
'The Hitch-Hiker's Guide To The Galaxy'
'Star Trek: The Next Generation' - "Inner Light"
'Pioneers Of Television' - "Science Fiction"
'Star Trek' (the original series)