I haven’t been to Newark, Delaware. But I’ve been to Newark, New Jersey and Newark, New York.
Alexandria in Ohio and Virginia
Ashland in Ohio and Kentucky
Hamilton in Ohio and Ontario
Harrisburg in Ohio an Pennsylvania
London in Ohio, Ontario, and England
Monroe in Ohio and Michigan
Richmond in Indiana and Virginia
Toronto in Ohio and Ontario
Washington in Pennsylvania and the District of Columbia
Windsor in Ontario and England
Off the top of my head:
London, England and Ontario
Washington, DC, IL, and PA
Orange County, FL, CA, and NC
Gainesville, FL and GA (same day, while living in the former)
Jacksonville, FL and IL
Bloomington, IL and MN
Oxford, England and MS
Richmond, VA and IN
Vancouver, British Columbia and WA
Peru, the country and IL
Bloomington, IL, Bloomington, IN, and Bloomington, MN
Springfield, IL, Springfield, OH, and Springfield, MO
Danville, IL, and Danville, IN
And, three different spellings, but all named for the same Indian tribe:
Menomonie, WI, Menominee, MI, and Menomonee Falls, WI
Philadelphia, PA and Greece
Paris, TX and France
Las Vegas, NM and Nevada
Athens, TX and Greece
Kingston, New York and Kingston, Ontario
At least a dozen Greenvilles in the US. There’s a boatload of them. Oh, and one in Nova Scotia.
The ones I know of:
Portland, ME and Portland, OR
Lots of Greenville’s
Lafayette, GA, Lafayette, LA and Lafayette, IN
Springfield, IL and Springfield, TN
Monroe, GA and Monroe, LA
Oostburg, Zeeland, Netherlands
Oostburg, Wisconsin, USA
People get 'em confused all the time.
I’ve been to Montgomery Counties in Alabama, Ohio, and Maryland.
I remember wondering as a little kid why the Book of Revelations (yeah, I read way above my grade level) had John writing a letter to the church at Philadelphia but not to the church at New York, DC, or Boston.
In Toledo Spain, there’s a street less than one block long, named “Toledo, Ohio.” Any other places have something like that?
Been theres, done thats. On the Greyhound bus. 
I live in Colorado Springs, Colorado. That’s doubly redundant, so we just call it the Springs.
Only within a mile, not actually in, but Cambridge, Cambridgeshire and Cambridge Gloucestershire.
Concord MA is 60 miles from Concord NH which is 100 miles from Concord VT.
I’ve passed through the ones in IL, IN, and KY. A lazy search turned up (in the US alone)
Illinois, Indiana, Iowa, Kansas, Kentucky, Maine, Minnesota, Missouri
Two Aurora’s in New York, one in Cayuga County and one in Erie County
Nevada, North Carolina, Ohio, Oregon, South Dakota, Texas, Utah, West Virginia
Two Aurora’s in Wisconsin, one in Florence County and one in Kenosha County.
I’ve been to centerville Ohio and centerville Ohio, as well as Oakwood Ohio and Oakwood Ohio.
Paris IL and Paris France (breaking the streak of people going to Paris TX)
Bloomington IL & Bloomington IN (this one seems common)
Atlanta (GA & MI)
Aurora (OH & IL)
Auburn (MI & IN)
Augusta (GA & MI)
Bay City (TX & MI)
Bloomington (IN & MN)
Brooklyn (NY & MI)
Carmel (CA & IN)
Charleston (WV and SC)
Coldwater (OH & MI)
Columbus (OH & IN)
Houston (TX & OH)
Lima (OH & Peru)
Monroe (MI, OH & LA)
Newark (OH & NJ)
New London (WI & OH)
Niagara Falls (NY & ON)
Sandusky (MI & OH)
Union City (IN & OH - also at the same time!)
Close but no cigar - Sidney, OH and Sydney, NSW AU