The script generates different URLs for normal browsers and different URLs for robots (GoogleBot.. Yahoo, etc).
The "customer URL" to the product on category page has page number and category number in it, and "robots URL" does not have that.
How can you see that?
If you came to product from category it looks like this
http://www.soundchoicestore.com/brick-karaoke-c-18-p-1-pr-651.html
and it is UNRANKED in google (NO PR)
But if you search for the same product/url in google, you'll find URL
http://www.soundchoicestore.com/brick-karaoke-pr-651.html with PR2
These means that script is serving different URLs to customers and different to robots.
It is called cloaking and it is what big SE frown upon. Although is very minor cloaking, but are you prepared to take chances with it?