You found the Games Quarterly #11 mini expansion. It was published and released in that magazine several years ago by Rio Grande Games, I believe. It has twelve tiles, two of which are used with/to replace tiles from the River I or River II; those expansions are indeed used instead of the normal starting tile (you would need one of the River expansions to work those two tiles into your game). The rest of the tiles have different configurations than could be found in any expansions up to that point. From your other post, I'm guessing that you have a version of Traders and Builders that doesn't have a pig watermark on the tiles, so yes, taking a picture would be a good way to remember those tiles are separate.