pgt: Though there's other things I can find fault with in the implementation of the autopass, I have heard a justification for this. It is rare, but someone might want to offer a double from that position. I have had people do this against me. Apparently, when it has happened to me, the person didn't offer the double earlier as they were going for a gammon and I messed that up by hitting them. And there's other situations for it too, such as they forgot to double earlier. :)

Maybe you would never offer a double with a piece on the bar, but some people do it.