Hi there, faissal.
I'll provide information and steps so you're able to sync or import your customer's information in QuickBooks.
Yes, when you sync or import customers in QuickBooks, it's necessary to be unique. This is because the system won't allow you to use the same information.
Currently, there's isn't an option to sync customers in QuickBooks with the same name. It won't work even if you will map the Email ID to the name field of the customers. However, I suggest putting extra characters in the customer's name to allow you to import them.
I attached a screenshot below for visual reference on how adding extra characters should look from Excel.
You can click this article to see detailed steps on how successfully import your customer's data in QuickBooks: Move your lists to QuickBooks Online. This also provides information on how you can import other lists and export them to the system.
Please check this article on how to add, delete, merge, and restore customers in QuickBooks Online: Manage your customer list.
Please know that you're always welcome to post if you have any other concerns. Wishing you and your business continued success.