Don't worry violin1000,
It's not a problem. It doesn't bring down the value in my opinion either. Guarneri was known for making differences between f-holes as a matter of fact. It kind of makes it look a bit more hand made.
If it really bothers you, you can perhaps alter one of the thinner, smaller, whatever, f-holes to match the other.
The Ole Bull is famous for this issue.
The sound is possibly not affected but could be affected either way. Better or worse.