But there is a possible chance to get it back. Often scammers are not carefully enough when cashing out at an exchange. Between your transaction to the scammers and their potential transactions to an exchange their wallet might have combined the coins with other ones. Assuming they scammed hundreds of people they might make a mistake and we might be able to trace the coins to an exchange address and the exchange might have a bank account number or id. There are millions of addresses of exchanges known nowadays so this can be matched with forensic analysis, clustering scammers addresses and transaction outputs.
The very smart scammers won't be catched, but many have no deep knowledge about Bitcoin forensics and do something wrong what can reveal their privacy now or in future. I could describe here as well when it's nearly impossible to catch them but don't want to teach scammers reading here... . The more people they scammed the higher is the chance to catch them. Always it depends on your, the scammers and maybe an exchange jurisdiction.
My suggestion:
- Review if this loss can reduce your taxes
- Send me a direct message with the transactions where you transferred 0.5 BTC twice. I feed my forensic tools with it to see if any traces already went to known exchanges. If no outcome this can be repeated, unlikely they don't move the coins earlier or later.
- We can attack the scammers to increase the chances that they reveal their identity unknowingly.
- Report it to police (then you might get something back if others catch the scammers in future)