Hello, with help of the "net view" command in Command Prompt window, I was able to determine what were the duplicate name here. It happened that we have a Linux server for some maintenance programs to run, and our colleage created a shared file in it to be able to access from Windows, and the name of sharing was the same name as the GROUP in the Windows workstations, so the message disappeared when we changed the GROUP name in our machines. The complete solution for us will come when our friend comes back from vacation and change the shared name to anything different.
MisterVSE