Double spend risk allows a holder to spend the digital currency twice. It is a potential problem unique to digital currencies. Digital information on the blockchain is reproduce-able by savvy individuals or strong miners who understand the blockchain network and the computing power or hash rate necessary to manipulate it.
Double spending occurs when a blockchain network attack happens and the malicious actor steals your cryptocurrency. The thief would send a copy of the currency transaction to make it look legitimate. They might erase the transaction altogether.