Someone has already added that SSH key to another account.

[alexd__web]

How can i find the account i have my ssh key added?

[Ben]

G'day Alex! 

My name is Ben and I am from the Bitbucket Cloud Support team.

Allow me to step in for this case as this will require some investigation from the backend and will require sharing sensitive information relating to workspace/repository names which would not be appropriate to discuss on a public forum such as this.

I have opened a ticket in our support portal on your behalf, you should receive an email shortly - we will continue our conversation there.

Cheers!

- Ben (Bitbucket Cloud Support)