I don't know why you think that 1 would produce 1 and 1 would produce 1 .
If you look at the details tab of the coinage (when it isn't buffed) you see it requires 4 for 1 .
If you look at the details of the gold smelter (also not buffed) you see it requires 2 for 1 .
So you need 8 to produce 1 .
If you buff with (Aunt Irma's Basket) your output multiplies with 2, so that would make:
4 for 2
2 for 2
So you need 4 to create 2