This is possible Mushahid, as long as the user that is logging in has a Digital Line with a RingCentral deskphone or softphone. The user should be able to log into two RingCentral for Desktop softphones as well as the RingCentral mobile app on iOS or Android.
One user can be logged into two separate PCs simultaneously. However, you cannot have two separate users logged into one PC simultaneously, even if they are on separate user logins on the PC.
If a user attempts to log into more than 2 PCs they will get a message stating that they have reached their limit of additional softphones and the app they are logging into will only have the ability to use the RingOut feature.