playBunny: I was using the latest version from the Ubuntu repositories, so until your post I just assumed it was fairly recent. I just downloaded the latest snapshot and installed from source, and voilà! it changed and tells me that "Double, take" is indeed the correct action.

So it seems like some glitch that was introduced and fixed between your versions, or maybe some obscure error resulting from the package building process. It could always be a bug in one of the libraries used, etc.

Anyway, thank you all for your assistance, and for restoring my faith in GnuBG, and my certainty that it is smarter than I am ;)

I don't have the mat file on this computer atm, and do not remember what match it was, but the position ID was AwAAEAEAAAAAAA