Sell downloadable products attributes

To sell digital products ... attributes may become obsolete?

For example:
sell a product with the following attributes.

pdf doll house price $ 1 Dollar
dxf doll house price $ 1 Dollar
pdf and dxf doll house price $ 2 Dollars

How to make my client who wants to download
If it is the same product, one that is different extension.

I have to make three different products or I can fix this with the attributes?