I don't quite understand the already sent input thing. I know how that would be possible with bitcoin core etc but the address I got the person to send to is actually my local coins address which does not allow any kind of transactions like that,
as in localbitcoins.com address? if so then this is your answer:
LocalBitcoins Wallet is a web wallet. Sending and receiving transactions are not connected to each other. If you are looking at your LocalBitcoins.com Bitcoin address on Tradeblock.com or from any other Bitcoin transaction exploration service you will see transactions that don't belong to you.
This is how web wallets operate. You cannot make connections with incoming and outgoing transactions for the same Bitcoin address. This feature is shared with all web wallet services.