Trading replacement, double flowers
These two is not a concept, usually replacing the transaction need to follow BIP125 (RBF) protocol, use locktime, sequence two fields with the selected node package to make one relatively high transaction fee, while ignoring the other transactions, specific agreements content, reference: https://github.com/bitcoin/bips/blob/master/bip-0125.mediawiki .
BIP125 agreement to comply with trading rules replace: the first node receives a processing fee lower transaction subsequently received a same structure but before the transaction fees than trading high of transaction, then the node will be removed out of the low fees transaction, instead of receiving high transaction fees.
The accepted rule double flowers transaction are: The first node receives the transaction is considered a legitimate, if the latter received a utxo spend the same transaction, the node later rejected direct trade, and gives the following error:
error code: -26
error message:
txn-mempool-conflict (code 18)