I would look at all the wallets on one system and on the other to see if you have the same or if you are sending from one address to another to check the tx out on blockchain.
If one is saying you got x amount and another says you got another amount and you know the table is correct then would indicate your other system does not have the addresses on it you could import them or just send all your coin to an address you have access to and then start sending where you need to.
If you are saying its sent but you did not send it then maybe look as to where they have gone or back trace to see if you really sent by mistake or something you might of sent to for some reason and forgot about it.
I would just locate all coins on both devices and then send them all to 1 address if i does not add up to what you have then I would start looking at where the other coin has gone to or some address you do not have access to.
According to what he said, he has generated address(es) in his tablet which is not imported in Multibit. Obviously, this will make two wallets to show different balance. However, I don't really understand what happened when he sent BTC to new address. I think his wallet is out of sync and they might caused it. Let's see whether he can see that transaction in explorers.
