Fortunately. But problems and surprises in informatics are always in the minority of cases. :-)
 

Settlements are drawn together and dissected all the time. Rome may be one city for one Wikipedia, separate ancient Rome and modern Rome for the other.
The newest problem in huwiki is a small part of Budapest that has two articles, one for it as part of the modern city, and one for the historical standalone settlement (same place, same name). Some wikis sraw articles together for notability reasons, others dissect because of extent.
 

These are really interesting! Can you tell what Germany is in the terms of history? Or just Prussia? Prussia is a country that's name leads to a disambiguation page in many wikis, and no warranty the standalone articles will match. Or what about Yugoslavia as a country? One wiki may think to write one article about countries by this name, while another will handle it in several articles.
 

 One wiki writes one article about Leonardo's paintings, the other one for each. This may be handled by linking to section titles, perhaps? While entities have a clear meaning, articles about them may not exactly match.

The same: one article about the moons of Uranus vs. one for each.
 
Etc.