Enumeration for Monarchs, eg: Alexander II

[abou]

Kings would be differentiated by a given surname of some sort. How that was granted differs between examples. So for example, you wouldn't see Antiochos I and Antiochos II or Ptolemaios I and Ptolemaios III; instead you would see Antiochos Soter and Antiochos Theos or Ptolemaios Soter and Ptolemaios Euergetes.

It's a bit more complicated than that, but that is the simple rundown of it.

[keravnos]

It would be cool if they did, but they didn't. As such there is a controversy as to whether there might have been one or two, especially when a son with the same name succeeded his father.

Demetrios 1 and Demetrios 2 (First two kings of the IndoGreeks) are often thought to be one person and even the existence of the later is doubted.

See...
http://en.wikipedia.org/wiki/Demetrius_II_of_India