We're aware of a situations where mounts can appear to have duplicate skills, like this:

If you encounter this issue, we can resolve it by deleting the mount and sending you a new one. You can request this resolution by clicking the button below. 

Please note:

• Any items equipped on the mount will be destroyed when it's deleted. To avoid this, please remove all equipment from the mount.
• It is quicker and easier for us to locate the mount if you've placed it in your character's inventory, but please be aware that it may still take some time before the request is processed.