We all know about the double mounts being the turtle and the panda, but honestly they are expensive as hell. I propose there be a double mount saddle sold at the stables. With this you get a selection screen that shows all your mounts. You click on the one you want to attach the double saddle to and it will attach it. Now obviously this wouldn't show up on your horse, but kind of like an upgrade to it. You obviously wouldn't be able to attach this to the already available double mounts. I think this would be a more of a affordable way to have people ride on your horse.