Someone has already added that SSH key to another account.

[Kal Zheng]

Someone has already added that SSH key to another account.

Kindly find the account that has the ssh key

[Nic Brough -Adaptavist-]

Welcome to the Atlassian Community!

There's no easy way to work this out because the keys that belong to other accounts should not be shared.

If you shared the key with someone, you should know who.  If you were given the key by someone, then you'll need to ask them.  

If you have no luck chasing it down, you can raise a support request with Atlassian, and they can search out the key for you and hence identify the account you shared it with.

If you don't want to spend ages chasing down the share, then you can (and should) create a new key for your account and use that instead.