Error 1001. the specified service is already exist

Question

I am having my window service installed with permission to everyone

but when i am logged in with another user and click on shortcut to access this service then its tries to re-install the service and gives an error message

"Error 1001. the specified service is already exist" And after this message its tries for uninstallation and able to uninstall some features.

my question is that if i have installed it for everyone then why it is trying for re-installation.