It's a funny cultural thing that it wouldn't have even occurred to me that someone in Europe wouldn't realize city names can conflict—it's a chronic problem here in the states.
There are some ridiculously common city names here, but one that's been in the news lately and probably confusing a lot of people is Springfield, which is the name of at least 42 different cities in the US [0], including 5 just in Wisconsin. Most of them are small, but 5 of them (Massachusetts, Missouri, Illinois, Oregon, Ohio) have more the 20k residents.
The long-defunct literary magazine Wigwag ran a monthly essay by an Angolan writer named Sousa Jamba titled "Letter from Springfield." For each installment he visited a different U.S. Springfield.
Plenty of European countries have conflicting city/town/village names as well. If they grow to large they are sometimes specified by adding more locality to their name.
Denmark has three cities names Nykøbing, typically specified as Nykøbing Mors, Nykøbing Sjælland or Nykøbing Falser. Small places are just allowed to conflict as long as they aren't in the same postcode.
In "Frankfurt-Hahn" the "Frankfurt" is still the same Frankfurt you (probably) wanted, you just got a different airport located further out. "Frankfurt an der Oder" is on the other side of Germany on the border with Poland, a ~7h drive away.
So this is more like you going to NY and landing at Newark when you expected JFK where Frankfurt an der Oder would be like ending up in New York, Iowa.
My favourite thing about the Newcastles is that one is under and one is on. I was pondering just recently whether there's any other under/upon pairs in the UK.
Yes, There are multiple Springfield in Wisconsin, multiple Madison in Pennsylvania and multiple Clinton in New York. These are some of the examples I remember. And yes it is annoying if you live in one of these towns.
Okay but how do you agree in which Springsteen, Wisconsin to meet? How do you tell your favorite navigation software where you're going to be departing from? How is this disambiguated if not by country and state combined?
FWIW, Wikipedia has a list of the most common place names in the United States. "Washington" leads at 91, which means nearly two occurrences per state, though this includes variant names such as "Old Washington", "Port Washington", and "Washingtonville":
Other issues you might want to consider are locations with multiple names or spelling variants, say, "Ciudad de México" and "Mexico City" or Pretoria/Tshwane, various script variants, or disputed names. Or closely-paired locations, such as Minneapolis / St. Paul or Dallas / Fort Worth. Or those which have changed names (Bombay / Mumbai, Calcutta / Kolkota, Madras / Chennai).
For the United States, using MSA (Metropolitan Statistical Area) will tend to group people by urban region, with less ambiguity and grouping of reasonably proximate locations. Unfortunately there doesn't seem to be a widely-used standard elsewhere.
Cue: "Falsehoods programmers believe about geography"
Much harder to geolocate internationally. You really need a geocoding service that accepts flexible input text, narrows the result set, and lets the user pick one.
“Las Vegas” means the meadows. The Spanish were usually pragmatic when naming locations on their maps, e.g. Del Rio, El Paso (de Norte), and Presidio in Texas; Salida, La Junta, and Pueblo in Colorado; the Sierra Nevada in California; and El Camino Real’s everywhere.
And to keep in mind, cities are mostly unique in a state but not entirely. There was another Oakland California twenty years ago. I don't know if it still exists 'cause Google no longer works for discovery of things like that.
Matt Groening grew up in Springfield, OR (also Portland, the streets names sharing a lot of character's names), it was only after he placed it in Springfield that he realized Springfield could be anywhere. He apparently makes direct references to local landmarks and establishments, and certain characters are rumored to have been based off of locals.
