It is really annoying to have two kinds of MGO (waves and ethereum chains) and they are not interchangeable in exchanges, unless you pay extra trading cost among various markets. Why don't the developers team do something for setting up an official site for 1-to-1 exchange of MGO acrossing two platforms? I think most people will happy to pay for the transfer cost (not cost of trading gap).
Is there any such site exist?

a tokenswap by the team is planned .. I think est was about 1 mtnh after release of the token .. correct me if I'm wrong.
That will not happen. Otherwise there's no point in dividing between two chains. I assume one of these will die out fast because of natural selection. Crowd wisdom has already shown that splits and hardforks such as ETC\ETH result in nothing but a series of damaging consequences that, I presume, will also happen here unless only one chain is chosen as primary.