Just to make sure we are on the same page, let me explain what is and isn't possible with products images w/options.
You can upload as many images for a single product as you like. So, if your product has multiple variations (different sizes, colors, etc.), you can upload images for all those variations. This instantly creates an image gallery that shows up on the product's detail page.
When adding images, the image that is listed at the top will be the image that shows first on the product detail page, and the image that shows on the catalog page for that product's listing. You can drag and drop each image if you wish to change that order and have a different image be first.
What you cannot do...
We currently do not have the ability to specify an image for each individual variation. So, when a customer chooses a different option from the dropdown on the product details page, the image will not change. We might be able to do something about this in the future, but we think this is going to be an acceptable limitation for launch, as it is likely that a customer will go through the product images to see the variation they are looking for.
I do not think that what you are asking for is currently a feature. There is not a way to have two different images for a single product. Such as one image for the catalog, and a different image as default on the product details page.
Am i understanding you correctly?
As always, thanks for your feedback and for testing things out. Let us know if you find anything else.