Why does my phone number appear twice under my Apple ID’s “reachable at” section?

One instance distinguishes itself (faded white lettering provided under each of the linked comm. sources) as being the associated number configured to my iMessaging and FaceTime services.

While the other instances of the same number does not provide any identifiers for its intended use. However, if I attempt to remove this unassigned comm source, a pop-up appears stating that by removing this unassigned number I will lose the iMessaging, FaceTime, and cloud sharing functionality for my Apple ID.

So it appears both instances of the same number essentially manages the same services, aside from cloud sharing, which is only noted as a managed service for the unassigned instance.

If you have any information regarding this irregularity please offer any insight you may have. However, if your only suggestion is to remove one or the other from my Apple ID, please refrain from commenting. These suggestions will not be considered helpful nor enlightening when it comes to diagnosing a reoccurring system irregularity. Thank you