Bitpay unused address - has balance
Bitpay/Copay use Hierarchical Deterministic wallets so you can find all the adresses that has been generated from your root private key (seed recovery phrase)

Here is a guide with more information: https://github.com/OmniLayer/omniwallet/wiki/Finding-and-Exporting-your-private-key-from-Bitpay-Copay