This is basically IDEX (Independent Dual EXtruders) printing. Usually they will have two toolheads on one gantry, but there are some that have more than one gantry. There are pros and cons to both configurations, and compared to tool changers.

The market seems to be heading toward tool changers currently (they are kind of the “new-hotness” right now) because you can fit more of them in a smaller space and there is less weight on the gantry (which means better prints at higher speeds) and they produce a lot less waste material than the AMS-style multi-material printers.