Magic Site placement

[Olm]

So a province can have a maximum of 4 sites.

Is the site type totally random (not considering requirements for sites) or is there something like an "only one gorgeous site per province" implemented?

Can I theoretically have for example a province with Const 20%, Ench 20% Alt 20% and Conj 20% all at once?
Or a province with Tower of the Golden Order, Tower of the Iron Order, Tower of the Silver Order and The Underworld?

Currently I have a province with Tower of the Golden Order, The Doom Cloud, Singing Stones and a Great Silver Mine and wondered how much better it could get. (Income for that province: 2F 3S 3A 2D 1E 60gp and Adepts of the Golden Order as recruits)

Has anybody for example ever had a province with the maximum of 20 Gems income?