If there's one thing cryptocurrency is supposed to guarantee, it's that no one can spend the same coin twice. Every transaction ever made with Bitcoin, ...
source https://www.google.com/url?rct=j&sa=t&url=https://www.cnet.com/news/ethereum-classic-cryptocurrency-pulled-from-trading-site-after-attack/&ct=ga&cd=CAIyGmM2Nzk3ODA2ZWViNjVjODI6Y29tOmVuOlVT&usg=AFQjCNFYlOjRLBi5IGX0Dqw_o-uo0biLaA
