Have 2 movies in 1080i@25 resolution
Then Kodi playing at 50fps is correct, because Kodi only outputs progressive, so it must render each interlaced (half) frame as a full progressive frame and you need 50 frames to account for 25 interlaced frames.
I lose frames at 50 refresh rate
I normally recommend people re-rip from the original media when the encoding is bad, but you've stolen a movie off the internet that's been ripped into a lossy interlaced format. I guess that made sense to the original pirate that created and shared it.
The only issue I can see is that you're expecting a lossy pirate rip to be high quality ![]()