In 1911 the Civil Administration called in all the exitsing Parish Registers and had them copied - by hand of course.
It these copies that have been filmed by the LDS and probably the ones you are using. They can be identified by the "OFFICIAL COPY" stamp at the top of each page.
I suppose that the origianl Reisters are legally the property of the Parish Churches but I think most, if not all, the historical ones have been deposited with Manx Heritage. It would fill a big hole if the LDS could either film or get copies of the MH films of these items.