1
general::
Phrase(s): kill two birds with one stone
Fig. to solve two problems at one time with a single action. • John learned the words to his part in the play while peeling potatoes. He was killing two birds with one stone. • I have to cash a check and make a payment on my bank loan. I’ll kill two birds with one stone by doing them both in one trip to the bank.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Achieve two ends with a single effort, as in As long as I was in town on business, I thought I'd kill two birds and visit my uncle too. This expression is so well known that it is often shortened, as in the example. [c. 1600]
American Heritage Idioms