I cannot add ssh key

[anandabiswas1991]

Someone has already added that SSH key to another account.

[Vinicius]

Hi, @anandabiswas1991, welcome to the Atlassian Community! :)

As we will need to know the public ssh key to further investigate this case, I have created an internal ticket for you using the email of your community account, so you don't have to share this information here. 

You should have received an email with a link to the support ticket. Just in case you haven't received it, please feel free to let me know and I can post the ticket URL here. The ticket will be visible only to you and Atlassian staff, no one else can view its contents even if they have the URL.

Please feel free to let me know if you have any questions.

Kind regards,
Vinicius

[Nic Brough -Adaptavist-]

Welcome to the Atlassian Community!

This means that you are trying to re-use an ssh key that you've used with another account, you gave a key to someone else, or they shared a key with you.  You should not do that. keys should be unique to an identity.

You can ask Atlassian where it might have been used, but the best thing to do is create a new key for your new account and not share it.