No, you weren't imagining it. There are so many names for chillies and some have more than one name. The chilli normally known as Ghost is a version of the Naga Ghost and sometimes called known as Bhut Jolokia and Ghost Jolokia. The Reaper is another version of the Naga. The Naga seems to be the base for most of the very hot chillies. It is supposed to have originated in Nagaland (no that's not a joke). Nagaland is in the foothills of the Himalayas and bordered by Burma, Assam, and close to Bangladesh and Bhutan. The home of the Naga chilli is now in Bangladesh and their favourite chilli. It is based around Sylhet (not far from Nagaland) and the majority of 'Indian' restaurants in England are actually Bangladeshi restaurants originating in Sylhet.