I have competed, and trained in both wrestling and Judo, in the last 20 years the rules of competitive Judo have changed so much, that the two sports are like apples and oranges to me. With that being said, you could still benefit from training either discipline.
To answer your question more specifically, it would be next to impossible to be an Olympic Champion in both sports. If you want to get really good at something you have to stick to one thing at a time. This does not mean you can not borrow moves from another discipline and apply to the other. Steve Mocco had a great foot sweep, that he successfully used in wrestling that came from Judo.