A new record! These two are within a couple years of one another-- the one on the right is set before Julius Caesar's assassination, and the one on the left begins a year or two after it. The one on the left has been way more fun to read, however.
Unless it gets creepy and non-consensual (sadly, a common trope), Zebra Historical Romances are terribly entertaining to read and always have the best cover. Nothing, though-- absolutely nothing-- can beat the cover of Viking Ecstasy.