How to import custom tokens when importing an account

I am trying to import an account from a Metamask wallet on another PC. Whilst I successfully imported ETH I had in my other wallet, my custom tokens (DPR) did not come through to the new Metamask wallet. I get an error when I use the private key from the original wallet stating - ‘The account you’re are trying to import is a duplicate’. How do I resolve this error and successfully import my DPR tokens?

Nope, not yet. Any suggestions?