Place meat in a large plastic bag set in a shallow dish. For marinade, in a food processor bowl or blender container combine chipotle peppers, orange juice, onion, oregano, lime juice, honey, oil, garlic, and salt.
Cover and process or blend until nearly smooth. Pour over meat. Close bag. Marinate in refrigerator for 2 hours. (Do not marinate more than 2 hours because the citrus juices cause meat to become too tender and mushy.) Drain meat and discard marinade.
In a grill with a cover, arrange preheated coals around drip pan. Test for medium heat where meat will cook. Insert a meat thermometer near the center of one of the tenderloins. Place the meat on a rack in a roasting pan on the grill rack. Cover and grill for 30 to 45 minutes or until meat thermometer registers 155 degrees F.
Remove pork from grill. Cover with foil; let stand 5 minutes before carving. Garnish with oregano leaves, if desired. Makes 6 main-dish servings.