I am not quite sure I fully understand your setup - but I think you are saying you have one product that you offer in 6 formats. And currently you are displaying 6 different products so customer can order just the format they need. And you would like to have ONE product that customer can select the format for.
If this assumption is right- then perhaps this would be a solution for you - you can add each format in the download section for the ONE product. Then on the description of your product you would say which formats it comes in
When customer goes to their download page they would see all the formats and make the selection.
You just need to label each of your files so customer can see the format
you can call them anything on the name (not the mask)
Radial Stamp - PNG Format
Radial Stamp - JPG format
This method would allow you to have one product desc for all formats.
The downside is if you need to charge for each format for the product - this would not be the solution.