I made a new site and noticed that the CMS I used tends to duplicate content.

i.e., if a user post a page about evil aliens attacking the moon, the "summary" will appear in:

the main content page
in the tag pages. ie, if the post has been tagged as alien and mars, the summary will appear in pages such as:

sitename.com/tags/alien/
sitename.com/tags/mars/

also, this summary will appear in the categories, ie

sitename.com/category/newcivilisations/

and, least but not last, in the user profile page, ie:

sitename.com/user/username/posted/

so basically, the same summary will appear in 5 different pages (at least).

this situation can be considered 'duplicated content' by a search engine?
as anyone else dealt with this before?
should I start to deny folders via robots.txt?

I am eager to hear your opinions.

[edited by: caveman at 7:37 pm (utc) on Jan. 8, 2007]
[edit reason] Removed specifics, per TOS [/edit]