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The BBC news website has hi-graphics and text-only versions of each page, and both are in the Google index.
My own website had a PDF file of an HTML article, and both are always in the index (sure the graphics are different, but the indexed content is 100% identical).
The only duplicate penalties I've had are when one page doesn't appear in the SERPS unless you click on the link to see the "other similar pages" (&filter=0).
I've never seen a penalty, just that one of the pages is demoted radically.
For you to get two similar pages about two similar cities, however, both ranking, you will certainly need to avoid this demotion, otherwise only one will show without the &filter=0.
It begs the question, of course, of why the pages are so similar if the cities aren't! Google certainly doesn't mind an *amount* of common HTML, otherwise navigation bars would kill all pages in a site except one. Surely most of the other content would be different?
Since it's a demotion, rather than a penalty, that you'll incur, it's not to tragic to try a controlled experiment on your own site. Changing the demoted page will bring it right back, unlike a penalised site.