While I'm not against similarities in names, it seems passing strange and more than a little redundant to see that Northern Mistone kingdom is named for the Whitehorn forest which dominates it, named for its lore - and Northern Belinara is dominated by this historical Great Forest in a last bastion of nature kind of way, in which the Great Oak is found and all sorts of crazy stuff, and its just called the Horn Kingdom, named for a Fort Horn which is a bit away from another Whitehorn.
I'm not sure what exactly the suggestion is, it just seems like the name was picked a bit randomly despite that it does sort of make it look like it's just copied from Mistone's, you know? I kind of doubt it was intentional, but suppose that if everyone is against changing it something could be written to account for the strangeness. Altering names isn't as hard as writing things around stuff though, so I thought I would mention it hopefully.