This question already has an answer here:

When I create a signed transaction on my offline computer and then broadcast it on my online computer. What hinders a node to broadcast it again after my transaction is included in a block?

marked as duplicate by Ismael, Achala Dissanayake, Richard Horrocks, flygoing, Roman Frolov Jan 26 '18 at 1:27

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.


I already found it out in the meantime. The nonce prevents double spends. Google Ethereum tx nonce to get more information.

Not the answer you're looking for? Browse other questions tagged or ask your own question.