Put lobsters into a large pot, cover with lukewarm water, and bring to a simmer over medium heat. This should take about 45 minutes in all. Meanwhile, put 2 ½ cups water, wine, carrots, onions, parsley, thyme, peppercorns, and bay leaf into a large nonreactive pot and bring to a boil over medium-high heat. When water in lobster pot comes to a simmer and lobsters begin to turn red, transfer lobsters to the other pot, cover, reduce heat to medium, and steam until lobsters turn bright red, about 20 minutes. Transfer lobsters to a sheet tray to let cool slightly, discarding cooking liquids.
Preheat oven to 350°. Once lobsters are cool enough to handle, remove their claws. Halve lobsters lengthwise. Extract meat from bodies and claws in pieces as large as possible and transfer to a warm medium bowl. Scrape out the soft, greenish tomalley (liver) from near the head area of the shells into the bowl. Cut meat into 1"-2" pieces. Place the empty lobster shells on a sheet tray and heat in the oven, about 5 minutes.
Melt butter in a large skillet over medium-high heat until just foaming, 1-2 minutes. Add meat and tomalley and toss until heated through, about 1 minute. Fill shells with meat and serve with melted butter and juices from the skillet.