We can save common credentials in RDTabs and while logging in we can select any of saved credentials or input new.

For eg:

We saved below 2 credentials in RDTabs

1) Credential Name: heyshubham, UserName: - heyshubham\admin, Password : *****
2) Credential Name: hey, UserName: - hey\admin, Password : *****

whenever we try to connect to new connection, we can select any of above 2 mentioned credentials, or simply pass new username and password.