I have never seen this before. I searched for widget supplies and the number 1 site is also listed #18. The number 1 listing is his homepage ie mydomain.com and the second listing is an internal category page domain.com/store/widgetsupply.htm.
My experience has always been that the second listing would com as an indented sublisting of the first listing.
I've seen it. It tends to be when one of the pages is "freshed" and the other is coming from the main index. I've even seen the same pages come up differently such as the "freshed" version as result #2 and the regular crawl version #15.
I have just set up a new computer and hadn't set my google preferences to 100 results per page yet - I just did and that 18th listing now is indented under his #1 listing.
2 listings is still the max for any domain, right?
I've found that too, cline. I've been trying to figure out when a domain with "www.", and the same domain without it, are treated as different domains by Google and when they are treated as the same.