Texts from a person via iMessage are coming from both their email and phone number separately

Since I upgraded my iPhone 15 Pro to iOS 18 a few months ago on the public beta(now off the beta and the issue persists), receiving messages from just one contact have been messed up, but only seen in notifications on the phone. My Macbook Air M2 doesn't have this notification issue nor does my Apple Watch series 9.

When receiving texts from this specific person through iMessage the notification on the phone states it is coming from 2 of the same person through a group chat, one saying "Maybe: FIRST LAST"(coming from their Apple ID I assume) and the other saying the name I have set for them in contacts.(screenshot below)

I have tried many things to solve this problem on my own:

• Deleting and re-adding the contact
• Changing settings to only send and receive messages from either email or phone number(neither fixed it)
• Disabling iMessage and using SMS
• Removing email or phone number from contact*

*About the last solution I tried, this one came with many other issues. In the contact of the person causing the issue, I have both their email and phone number listed. If I were to remove the email, the problem with the notification would be fixed, but all message history would disappear and in iMessage the contact would appear blank with no name or picture, just the phone number as the name. The same thing happens when I remove just the phone number.

I would also like to add that my contact for them on all their devices has no issues, its just on my end.

This issue causes no problems when trying to contact them in any way, but it just looks weird and has become quite annoying to look at over time and I want it fixed. If anyone has a follow up question or an idea for a solution, please reply😃. Thanks.