why when i log into my webroot account online i see that 4pc are currently protected(i have only 3pc), two of them are the same!?
It's possible that a hardware change has caused one to be identified differently. The support team should be able to find the cause without a problem
That makes sense. It has to have some UID to determine which PC is which, and so if the same PC sends two different UIDs to the system, it'll show up as two computers. Unless there is some way now for you or support to remove the extra PC (And then it comes down to "Which one is the right one to remove?", it should vanish after some time like the extras on my account did. Unless it's under the Backup and Sync, in which case you can remove it manually.