copyscape is as much a tool in my belt as modules on wizzley, even if I write something 100% fresh I copyscape it to make sure I'm not plagerizing MYSELF, when you write on just about any topic known to man it's easy to forget what you've already written, and since your writing is often a result of your character and mind set you may say things exactly the same as before and think your writing fresh witty content...
Peace of mind is worth 5 cents an article I think- then I know when I hit that button it will clear...
by the way, if a result comes up it means the content WAS, but may no longer be copied on another site. The 404 often is a result of them removing the page copyscape found when it was live (i.e. google's cache still shows a copy until the bot crawls the page again so the search results still show it copied, but when you actually click the link, the 404 comes (because it may be cached but is not live on the web where it was). This is a good thing, it means the person who used it (legitimately if they copied your bio over) decided to remove it.
If you go through that list of sites say you get 10 url's... this doesn't always mean there was any duplicate copies out there, just the lines in many cases. A rule of thumb is anything below 10% dupe content is ok. If you notice the wording on the wizzley warning when you publish it says "Do not copy large chunks of content that exists on the web, even if it's your own content" (I paraphrased from memory)...
Anyone who uses copyscape knows this rule (eventually), the reason is that there are phrases that may be a single sentence long but one that's very common and can't be said any other way so many sites will show up as using a sentence you may have used verbatim because of how we talk in general. These are usually the bulk of those links so check them all if in doubt, if it shows less than 10% duplicated content, check to make sure the content is ambiguous or if it's something you can change (like you did with that other one).
Another thing I've noticed is that the article with the most % of content showing duplicate shows up at the top of the heap. So it seems to be ordered by most to least copied. You can also tell by the size of the sample text they show below the links. If you see a thin few lines it's likely ok, if you see a large paragraph, it's likely duplicate content (over 10%).
hope this helps...
Jerrico