Manage Licenses-Protected Devices-One of my devices is listed twice

Brief backstory, followed by statement of problem, followed by question.
Backstory:  Our Norton 360 Deluxe Subscription allows protection for up to 5 devices.  We currently protect (1) our Windows PC, (2) an iPad Air 4th Gen, (3) 2 iPhones.  Total=4 devices.  The Norton 360 app is installed on the iPad and on both iPhones.
Backstory cont'd:  I also have an annual subscription to Norton Mobile Security that I purchased from the Apple Store.  I pay for this subscription IN ADDITION TO what we pay for our Norton 360 Deluxe subscription.
Statement of Problem:  My Account Norton.com says we have 5 of 5 licenses used.  Detail shows the iPad Air, the Windows PC, an iPhone named with a person's name, and TWO other iphones.  Further detail shows that the licenses for the "two other iphones" were installed on 10/6/22 and 10/9/22 respectively.  These "two other" are actually the SAME PHONE.
Statement cont'd:  I spent a great deal of time on the phone with Norton Customer Support on 10/6/22 correcting the problem of a duplicate listing for iPhones.  At that time, we deleted both offending licenses from the dropdown list, somehow re-added one, deleted the Norton 360 app from the phone, and re-installed the app.  That seemed to fix the problem.  However, the problem has recently re-appeared.

Question: (a) how can we resolve this problem once and for all so that we have a total of 4 licenses used (PC, iPad, iphone named, and ONE other iphone?)  (b) Does the in-app Norton 360 subscription cause the duplication, and should I cancel the in-app subscription?

First. You definitely do not need the Norton Mobile Security subscription from the Apple store. That is just a duplication and it would get your the new 360 app anyway. Cancel that with Apple so you are not charged again.

For the number of devices listed. Are you looking in your Norton Account in the Devices page? If so, that page is notorious for being incorrect. To get the correct information you need to log into your Account and hover your cursor over the user icon at the top right, then click on Manage My Subscriptions. Find your current 360 subscription and click on Manage Licences. That will give the correct information.