What do you mean with dual operating system? Like having both Windows and iOS on a single computer? I'm no expert, but I'm pretty sure that's not possible. Sure, you can download and run Windows software on a Mac, but then I think it would be like an emulator or you fully disable iOS, I don't think operators can coexist in another way.
Why do you ask? Sheer curiousity or do you have reasons why you want more operating systems on one device? Or isn't that what you mean by Dual Operating System?