Bitrise App with private pod


I have made a private Cocoa Pod to be used in my app. Based on these links: Private cocoa pod and ssh deploy key and , all I have to do is just use the same SSH key for the spec and source repo, right? Is it the same key with the Bitrise app’s public key? If it is, then how do I use it? Because when I added it in my Bitbucket repo’s Access Keys settings, it failed with the error message : Someone has already registered that SSH key. So how do I fix this?