Ethereum Block limitations

Question

I am considering writing a contract and can see potential problems (cheats) if multiple transactions/calls are allowed per block for the same address.

When I say "transaction/call" I am meaning a function that will modify the blockchain.

I'm not sure if my understanding is correct about how double spending is prevented and what implications it has on the blockchain. I think it limits transactions/calls to one per block per address and thus also prevents the potential situation I am concerned about (two or more function calls in an uncertain order).

Is each address limited to one transaction/call per block?

Answer 1

No, there's no limit on how many transactions per block can involve the same address. But the transactions happen serially in a defined order.

For two transactions that happen in the same block, the second transactions will be executed with the state that resulted from the first transaction.