This is mainly info found on various italian forums posts posted between 2005 and 2014, so take it with a pinch of salt. 

It apparently has been broadcasted on Italia1 3 times.
Of those 3 times, only the first one has been aired in full. 
The 2 following broadcasts have been stopped midway. (2nd broadcast after 63 eps, 3rd after 25 or 50)

During the last broadcast, they divided the episode in 2 parts, which is what we have here.
That would also explain why some sources said that 3rd broadcast ended after 50 eps, and some other after only 25.

I'm not sure what the original source for those episodes is, but the earliest version found was hosted on ToonItalia in 2014.
https://web.archive.org/web/20150326014522/http://toonitaliaanime.altervista.org/luna-principessa-argentata/
On it, 73 "half-episodes" were hosted, the 36 first episodes and the first half of the 37.
Several episodes that were hosted here are not available anymore and have not been posted anywhere else, hence why there's some episodes missing.