Never used Elytra Not Repairng

I found an elytra in one of the end cities in my world a few days ago and I never used it because I've had one already with Unbreaking 2 on it. I've repaired the unbreaking 2 elytra a few times where I couldn't repair it anymore because it was Too Expensive! I then started using the new elytra that I've found in the end cities, and the durability started getting low on the new one that I've found. When I went to go repair it in the anvil it said that it was too expensive. This is my first time repairing this elytra that I've found and it's saying that it is too expensive when I've never repaired this one Please help!