How to make user email unique based on user roles

I am new to laravel i am using laravel 6x. Now i want to know how to make user email unique based on user roles .I am using spatie permissions I have two type of users

• admin
• End user

Now i want to use laravel validation for same email for different roles,that means, email should be unique by roles. Anybody has any idea, please let me know

via Chebli Mohamed