Having X block in Y position makes the machine output one extra extra item type. In the wiki the multipliers just makes the machine give extra stuff or use less. Example: A multiblock "drill" that alone it does nothing on its own(exept consume power and whatever in the original recipe), but if under it there is a X block it would give out X resource. but a Y block would make it give out Y resource. Usefull to not have to make dozens on machines just to have this variation.