One of my current horses is called Denby - haven't come across another horse with same name so far.
Used to look after a little sh*tland when I was a teenager called Merry and when I helped out at a riding school at weekends, mainly looked after one called Surprise. Also rode a horse called Bomber.
But don't know the reason behind any of their names!
Mine are called Ricochet but gets called richie,chard or the chardinator and Eddie but he gets Dward (his stable plate says this) or the dwardinator,
Friend has one called valliant but farrier calls him violent