I doubt that since the other number is also my number lol. But I am not 100% sure. I tried your suggestion of deleting and re-adding and it still is not working.
I am having a similar problem. Two numbers from the same provider (Sasktel) calling but only 1 of them shows their caller display. And yes, both numbers are in my contacts list.
I have no idea if this issue has been resolved or not but I am currently having the same problem. Two numbers calling from the same provider, one caller display shows up, the other does not. Both are in my contacts list (IPhone 8 as well). I wonder ...