Every single modify on the ledger is cryptographically signed to confirm that the person transferring bitcoins is the actual owner. No you can devote coins 2 times simply because the moment a transaction is recorded from the ledger, just about every node while in the network will understand about it. https://howtobuynftart10663.smblogsites.com/28737244/manual-article-review-is-required-for-this-article