When I firstly install a new plugin, either through online installation or using downloaded local site archive, if I cancel this first time installation, I got an error message of "Duplication Location" when I try to install it again. But it was not installed and I can never install it anymore. What I can do is to delete Eclipse and unpack an other one to try my luck again.
Sometimes I must cancel the installation process, since during the installation, the "NEXT" and "FINISH" button at the license page somtimes(with a high rate) remained DISABLED and colorred gray even if I accept the license. I can only cancel this installation. another bug?