Not that I know of.

Why would you want to use both versions to go to a specific website?

It is best to stick with one version of a domain in case both are available and working.
Firefox wants to make sure that you send the password to the correct domain and not to another domain and stores the submit url in some cases.

Thank you for your reply i need this because some websites opens with both options 'with and without www' i have saved password for example.com but next time i open www.example.com coming from google or referral. i forget that i have account for example.com. i have to check in password manager for accounts every time. so thats why i want to save password for both www and without www. sorry for my bad english