I get an error while trying to create a Project from an account, saying “You cannot have the same email address for more than one client”. How can this be resolved?

I get an error while trying to create a Project from an account, saying “You cannot have the same email address for more than one client”. How can this be resolved?

Sometimes it so happens that you have the same email address for more than one contact associated with a particular account. When you try to create a project from such an account, you get this error.
In such a case, change one of the email addresses and make sure that the email addresses associated with the contacts are unique.