There are countless examples of people just letting Copilot's "autocomplete" run wild and it ends up reproducing many lines of code, often verbatim, and not just single lines of code.
You need to bait Copilot really hard to make it output that. To the point where it would be much easier to locate and copy-paste the code directly from the source yourself. It doesn't happen accidentally and it's not how you normally use Copilot.
A lot of people seem to think changing the variable names makes it new code.
The count is like 5
Considering how easy it is to generate additional examples, I think it's higher than 5. Five big, popular blog posts, maybe; but there are way more than 5 examples just on Twitter.