How can I check for a duplicate node when rendering a view? This question is closely related to my other question posed a few hours ago:
How to make a node appear across *all* Taxonomy terms?

As a solution, I plan to create a functionality, where my new nodes are added to every country in my 'countries' vocabulary, when a 'check all' button is clicked (this is in addition to a single term in the 'main' classification taxonomy they are assigned to).

But I have a view for the display of these nodes. It accepts a term ID from the main taxonomy via URL, and provides a Hierarchical Select "exposed filter" for further filtering by geography within the displayed nodes.

I will now have the same node teaser multiplied by the number of countries in my vocabulary, when the user first enters this view (because that many nodes were created).

Is there a way I can tell my view to just notice such nodes only once, in the unfiltered state?
If I'm not mistaken, in your view-settings, you can select a distinct query in your Advanced settings in the view. It set under Query settings. I'm not sure if it's already there in D6.