Two creatures in one body?

Here's an interesting hypothesis I've never heard. Could Caterpillars and Butterflies be two separate creatures in a single body? Again, I've never heard of this, but it's one of those type of ideas that gets in your head and makes you think. Conventional thinking makes it difficult for me to believe, but then again I've never thought about it much either. The key idea here is that the explanation involves the caterpillar actually "dying" and the moth or butterfly constructing itself from the dead organic material left over from the dead caterpillar - not a continuous life cycle. Fun thought anyway.