DramaSpot lists 29 short dramas whose title marks them as dubbed, with the shortest shown below. Everything else plays in its original audio, and much of it was filmed in English to begin with.
Spotting a dubbed version
On DramaSpot a dubbed version says so in its title, usually as "(English dubbed version)". We take that label from the source and never guess, so an unmarked show may still be in English.
Dubbed and original are separate listings
A dubbed version gets its own page and its own episode count. If you would rather hear the original cast, search the same title without the label.
Dubbed dramas, shortest first
How these were chosen: by episode count alone, shortest first. We have no ratings, so this says nothing about which is good.