If my character give any meso or item to another character of mine by trading . does it break any rule?
Simple transfer of mesos between your own character is very common. No way that breaks any rules. Meanwhile if u ask ur friend to log into to your character to collect the items from the other end of the trade, will be against the T&Cs.
I mean my character gives meso or item to another character form other account. two characters does not in the same account.
Having more than 1 client open on mapleroyals is very common in the community. Whether you trade with yourself, party with yourself, train your other character or whatever, it does not break any rules on the server. As noted by Joon tho, YOU have to be the person controlling the game. For more comfort you can always ALT+Enter and the client will become windowed. One last warning to sum it up, trade. Always trade, never drop. People have lost so many items because they drop-trade to their other char out of lazyness and a random player walks by and picks up their valuable items.