I believe I made some mistake with my installation or configuration. I get several different url's to the same page? What's causing it? What can I do to fix it?

Example -

Original Question page -

Non-SEF, index.php?option=com_communityanswers&Itemid=347&id=2&lang=en& task=view&view=answers
SEF, qa/view/2-how-to-spray-lawn-weeds-without-hurting-grass.html

When I login to answer the question, the page turns into -

Non-SEF, index.php?option=com_communityanswers&Itemid=347&catid=2&id=2&lang=en&task=view&view=answers
SEF, qa/view/2/2-how-to-spray-lawn-weeds-without-hurting-grass.html

I don't have a clue where this comes from -

Non-SEF, index.php?option=com_communityanswers&Itemid=347&catid=3&id=2&lang=en&task=view&view=answers
SEF, qa/view/2-how-to-spray-lawn-weeds-without-hurting-grass/3.html

If I place all three of these url's in my browser, they all three go to the exact page. I've deleted them for now, but they'll just be created again when someone logs in or out.

Surely, i have mis-configured something somewhere. Please let me know what I've done wrong.

Thanks for your help.