2000 Mustang Coupe with dual exhaust?

I have had a 2000 Mustang for a little longer than a year now and the check engine has been on forever, I just went to get it inspected and apparently 4 of my 6 oxygen sensors are defective. I was going to fix the problem by getting new mufflers at a junk but I realized that my car has a dual exhaust and that Mustangs in my year come with a single exhaust. Would it be better to find a dual exhaust and keep it the way it is rather than replace it with a single?