Can i add new cust with same name? but different address unit no

Welcome to the Community, @shafinaz.

In QuickBooks Online (QBO), the ability to add new customer that has the same name with the existing ones is currently unavailable. This also applies to vendors and employees.

As a workaround, you can add extra character to the new customer's name so the system will not treat this as a duplicate.

I'll pass along your suggestion to our Product Developers. They're always looking for ideas to consider on how to improve QBO. In the meantime, I recommend visiting our Blog site. This is where we share recent happenings and future developments, such as updates to newly added features.

Just in case, I'll add this article for future reference: Manage your customer list.

Reach out to me in the comment section below if you have any other questions or concerns. I'm always here to help. Have a good one!