Thought Identification Puns

2 girls are chatting, one isn't particularly bright and seems very deep in thought, the other asks what she's thinking about, the not so bright one says she has an issue, "I have had a horse for years and my parents have just bought me a new one which is virtually identical to the first and I'm struggling to work out which one is which." The friend suggested she try cutting the mane short on one horse making it easy to identify. The friend is over the moon and rushes away to try the suggestion. A few weeks pass and the friends meet up, The friend and how she got on with the mane cutting trick. "It was fine for the first couple of weeks but the mane grew back so I'm back to square one." The friend thinks for a while and suggests cutting the hair on the tail short making identification simple. Again the girl rushes off to try the suggestion. A few weeks later they meet again with much the same story, this time the friend suggests measuring the horses height to see if one is taller than the other. A few weeks later they meet up, the not so clever one is ecstatic and proceeds to tell her friend how it went. "It was amazing and I hadn't noticed but the black horse was 2 hands taller than the white one".