1. Generate SSH key:

   $ ssh-keygen -t rsa -C <email1@example.com>

2. Generate another SSH key:

   $ ssh-keygen -t rsa -f ~/.ssh/accountB -C <email2@example.com>

   Now, two public keys (id_rsa.pub, accountB.pub) should be exists in the ~/.ssh/ directory.

   $ ls -l ~/.ssh     # see the files of '~/.ssh/' directory 

3. Create config file ~/.ssh/config with the following contents:

   $ nano ~/.ssh/config
   
   Host bitbucket.org  
       User git  
       Hostname bitbucket.org
       PreferredAuthentications publickey  
       IdentityFile ~/.ssh/id_rsa  
   
   Host bitbucket-accountB  
       User git  
       Hostname bitbucket.org  
       PreferredAuthentications publickey  
       IdentitiesOnly yes  
       IdentityFile ~/.ssh/accountB  

4. Clone from default account.

   $ git clone git@bitbucket.org:username/project.git

5. Clone from accountB account.

   $ git clone git@bitbucket-accountB:username/project.git

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