The problem is that if you convert from ePub 3 to ePub 2 using calibre, you get a the epub 3 code left it. So it's very much a mess.
This code is a line from a an ePub > ePub conversion and it's wrong because the ePub was originally ePub 3 and is now ePub 2. So there's a lot more work to clean up the errors after the conversion then before the conversion (in most cases).
Code:
<div epub:type="titlepage" class="calibre2">