Yes as long as your slow cooker is big enough you can cook two boneless turkey breasts together. I would recommend using a larger 8 quart slow cooker and doubling the recipe.
Cooking your Christmas turkey in a slow cooker guarantees juicy, tender results and frees up oven space for your trimmings. For this recipe you will need a large (5–7 litre) slow cooker.
Place the chicken, breast-side up, in the slow-cooker, pushing it down among the vegetables. Season all over with salt and pepper. Cover and cook on high for 4½ hours, or until the chicken is ...