I guess he was just dictator.
Imper Iter (”emperor”) was bestowed a few different times even before Julius Caesar; his mentor, peer, and rival Pompey held the title; Sulla I think also. I’m still looking right now...
Gaius Julius Caesar:
http://www.wildwinds.com/coins/imp/julius_caesar/i.html
Pompey:
http://www.wildwinds.com/coins/sear5/s1392.html
Sulla:
http://www.ancient-art.com/images/rr154.jpg