Have there ever been simultaneous cyclones in the same ocean but different hemispheres?
It does occasionally happen. Not often, because to kick-start a hurricane there has to be some rotation to start with, from the Coriolis effect, together with a sea surface temperature of >27 &deg;C (+ some other requirements such as lack of horizontal shear). This combination is best met during summer when one or other hemisphere is tilted towards the sun, so the hurricane seasons in both hemispheres tend to be 6 months out of synchronization. But there are occasional overlaps, as in this vector composite, found at http://www.wunderground.com/blog/JeffMasters/archive.html?year=2015&amp;month=06&amp;MR=1