In “Hot Potato Soup,” Agents of S.H.I.E.L.D. revealed that the agency had been working on a secret Life Model Decoy project years before Dr. Radcliffe even thought of A.I.D.A. Tony evidently knew enough about the project to joke about it in The Avengers.
In the beginning of The Avengers, Tony Stark referred to Life Model Decoys when trying to stop Coulson from intruding on a private moment with Pepper Potts.
It was a throwaway joke and nod to Tony’s habit of avoiding Coulson, but it also introduced L.M.D.s as something that had been invented in the MCU, and fans could only wonder when that happened and why we never heard about it.