I believe they were all made specially for the Bake Sale so it is unlikely anyone who hasn't bought the bundle will have played them before.
However, looking at the names of those involved, I would expect these to be well worth your while. They are all AGS developers that have some good games behind them. For example, the Ben Chandler game is obviously a spoof of Grundislav's highly acclaimed
Ben Jordan series and Technocrat is behind the low-res but brilliantly conceived
Technobabylon. If you search the AGS database for the names of the others, you'll find a similar history.
As far as I'm concerned, this is one of those times I'll feel guilty from the benefit I get from donating to charity.
It's 14 games, not 9 by the way.