Lets say in my Electrum wallet I have 0.5 BTC which I send to an address, and then a few seconds later send the same 0.5 BTC from my Electrum wallet to another address. (How will this even be allowed by the wallet? does it require hacking into wallet software?)

How is this double spend resolved? Is it chronological order, i.e. will the first transaction be accepted by the blockchain and the second one be rejected as the address does not now have enough balance?