Instances in which the Bible mentions animal twins do not follow the pattern. But it is interesting to note in the first instance the Bible mentions animal twins, The Song of Solomon 4:2, the words, "scarlet thread," appear in the very next verse. Furthermore in the next chapter (5:4), the bridegroom thrusts his hand through the hole in the door of his bride's sleeping chamber. It is not clear, however, that the bride inspects his hand to determine who he is as the bridegroom has already identified himself by speaking through the door.
Miracle of Old and New Testament Names