What has two left feet and likes to travel? Any one of the 150 sets of stereo siblings who came to Kansas City, Mo. last week for the 44th Annual Convention of the International Twins Association. Held to promote “the spiritual, intellectual and social welfare of twins throughout the world,” the three-day conclave also featured some partner-changing on the dance floor (disco and square), a visit to the rodeo and a Tigers-Royals baseball game. Highlight of the meeting, though, was a doubles contest in 23 categories, including oldest twins present (78), youngest (39 days) and the farthest distance traveled (8,400 miles from Hong Kong). The prizes? Matching trophies, of course.