They've definitely done something like it in the past. I think one aircraft did a BFS-LTN-AGP-BFS, while a second covered LTN-BFS-AGP-LTN in order to serve early AM arrivals to LTN and BFS on both legs. You could achieve similar with aircraft starting out from the same airport serving a foreign link in counterflow inbetween, but it's a complex bit of scheduling and one I doubt will become commonplace.