Britton (8-9) won his second straight start after dropping five consecutive decisions, holding the Yanks to four hits while issuing one walk and striking out five.
Vladimir Guerrero and J.J. Hardy drove in runs for the O's.
New York's Bartolo Colon (8-9) absorbed the loss despite allowing only two runs on seven hits in a 7 2/3-inning effort.
The Yankees came into the doubleheader trailing idle Boston by two games atop the American League East.
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