1. Rub roasts evenly with 2 tsp. salt and 1 tsp. pepper.
2. Brown roasts on all sides in hot oil in a Dutch oven over medium-high heat (about 10 minutes). Place roasts, side by side, in a 6-qt. slow cooker. Add carrots and remaining ingredients.
3. Cook, covered, on LOW 10 to 12 hours or until tender. Remove roasts from slow cooker; shred 1 roast, and serve with 2 cups vegetable-and-gravy mixture. Shred remaining roast. Store remaining roast and 2 cups vegetable-and-gravy mixture in separate airtight containers in refrigerator up to 3 days or freeze up to 2 months.
Slow-cooker Chuck Roast: Substitute 1 (3 1/4- to 3 3/4-lb.) chuck roast, trimmed, for eye-of-round roasts; reduce salt to 1 tsp; dried thyme leaves to 1/2 tsp.; and dried marjoram to 1/4 tsp. Prepare recipe as directed through Step 2. Cook, covered, on LOW 10 to 12 hours or until tender. Remove roast and vegetables, and shred meat. Pour gravy mixture from slow cooker into a 4-cup measuring cup or fat strainer, and let stand 15 minutes. Spoon or pour fat out of gravy mixture in cup or fat strainer, and discard. Serve gravy with shredded roast and carrots.