Unfortunately, the "state" we live in is sometimes listed as "Washington, D.C.," so one finds DC in alphabetical order after Washington and before West Virginia. When coupled with the name in the city field (Washington), this leads to an address in "Washington, Washington D.C.," which looks, sounds, and is ridiculous.
It appears that sometime in the last few weeks, Google Maps has fallen into a similar trap. Typing "Washington" into the search field when first in Google Maps, one sees the result below:
As you can see, they're labeling our city as "Washington D.C., DC." It's pretty silly.
Here's another example.
And finally, any address that you select (like the White House in this example) has "Washington D.C., DC" appended to the street address. Google needs to fix this, so the city name is only rendered as "Washington," and the state abbreviation is "DC." The current redundancy doesn't make sense.