In "Tortilla Flat," Steinbeck writes of towns he was familiar with, including Monterey, Carmel, Salinas, and Watsonville. These are translated in the Spanish edition as Monterrey (two "R"s), Carmel, Salinas, and Watsonville.
Why is "Monterey" changed? There is a Monterry, Mexico, and this seems like it could be confusing (which "Monterrey" do you mean?).
Is it for historical reasons? My guess is that when Monterey (California) was the capital of Alta California (when controlled by Mexico), it was spelled "Monterrey."
I would expect consistency in the translation of place names. If "Monterey" is translated as "Monterrey," why isn't "Watsonville" translated as "Aldea de Watson"? Ironically, the title of the book comes across unaltered: "Tortilla Flat" is entitled "Tortilla Flat" in the Spanish edition, too (not "Tortilla Plano").
To me, translating "Monterey" as "Monterrey" almost seems tantamount to a Dutchman translating "New York" as "New Amsterdam."
And this is not a patriotic/jingoistic reaction on my part; I agree with U.S. Grant that the war with Mexico (so conveniently occurring on the heels of the discovery of gold in California) was shameful.