You cannot set same ports for both http and https. You would have seen websites in which ports are not visible in case of http and https. It doesn't mean that those websites use the same ports. If, you set the port for http to 80 and https to 443. The ports won't be showed in URL. In case of ports other than 80 and 443, they will be shown in the URL.
If you did this, how would you know if it was using https or http? You'd never know if the parts that were supposed to be secure were secure. The browser certainly wouldn't be able to tell and subsequently the user.