Bring 2 gallons salted water to a boil in a large pot. Put in half the wine with the carrots, leeks, peppercorns, and bay leaf and boil for 15 minutes. Add the lobsters and boil for 13 minutes. Remove the lobsters and allow them to cool before removing them from the shell. Chop the claws, knuckles, and tail meat coarsely. Set aside. Strain the cooking liquid and reserve. Keep it on the burner at a simmer.
Heat half the oil in a Dutch oven or other large pan and gently fry the onion until soft. Stir in the rice and after 5 minutes stir in the remaining wine with the tomato sauce. Ladle in the reserved lobster stock a little at a time and keep stirring, adding more when it has been absorbed. After 15 to 20 minutes, the rice will be cooked (you will not use all the stock). Remove from the heat, stir in three-quarters of the chopped lobster, half the parsley, and the butter, and check the seasoning. Add salt and pepper as needed.
Divide into bowls and garnish with the remaining lobster meat and parsley, and drizzle a little lemon juice on top of each serving.