I just discovered Bosnia and Herzegovina has in fact three presidents, one from each ethnicity - Bosniak, Croatian and Serb. Is that the only country with such a thing, or there is/was more?
Lebanon has a similar system, where the President is required to be a Maronite, the Prime Minister must be Sunni, and the Speaker of the Parliament must be Shi'a.
Since this system was set up after 1995, it breaks the 20 year rule. Try r/ask_politics.