excerpt for BlogPosting

Hi,

I am currently marking up my Wordpress blog with schema.org microdata. 
My home page is a "classical" blog home page: it has a list of blog 
posts, each containing the excerpt of the post and a "read more" link to 
the full post. I am facing two situations which I don't know how to 
handle properly.

 1. I am missing an "excerpt" property for the BlogPosting schema.
    Should I use the "description" property of a "Thing" instead?
 2. A blog post will be marked up with microdata twice: once on the home
    page and once on the page containing the full post. Is that a bad
    thing, i.e. describe the same object multiple times on different
    pages? If there are no conflicts in the mark-up then I guess that it
    is not a problem. However, how is the case handled when for example
    the "dateCreated" property of the post on the home page is "DateFoo"
    and on the page for the full post it is "DateBar"? Of course, this
    would be a mistake by the developer of the web site but can it be
    detected in any way and how is it handled by search engines?

Thank you,

Regards,
Yoran


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