I'm sure that is true. That's part of the reason it take so long to get paid; they're waiting until the window to return the merchandise expires. My BoA rewards program does the same thing.
The six cents balance marked as "available" was also from fake transactions. Those transactions cleared after 60 days. If the system was automated, those transactions should have been canceled. I don't think they will actually do any checks until I try to withdraw the money. I don't plan to try that though. I think the part about blocking another person's transactions is actually the interesting part.