The "Duplicate Withdrawal Information" error occurs when you try to add a new withdrawal address with the same label (description) as an existing withdrawal address on your account.
All withdrawal addresses on your account must have a unique label; you cannot use the same label even if it is for two different cryptocurrencies.
For example: If you have a Bitcoin (BTC) withdrawal address called "My vault", you cannot add another withdrawal address for Ethereum (ETH) also called "My vault".
Instead, you could use labels such as "My Bitcoin vault" and "My Ethereum vault".