I can't seem to find any rules specifically on Mount attachments. Can characters have multiple mounts , as long as they don't exceed the blanket limit of 2 restricted attachments?

Thanks!

No limit. Load them up.

If you're looking for a thematic justification, spare horses for mounted soldiers is historically accurate -- though there's no evidence of the Rohirrim departing from one man, one horse. However, the Hobbit Pony is a mount (and Restricted), and the four hobbits left Crickhollow with *five* ponies.

Also if Movie Legolas can ride two dwarves in barrels then book/game one can easily stand up and ride on two horses.