Overwriting language links

Hi,

I have sites in 3 languages (CS, EN, SK). I usualy create post in Czech and duplicate it to SK and EN with Multisite Post Duplicator. Then I set language links through MSLS on each site. All works fine just until I make some changes in original (CS) site and publish it. SK-CS and EN-CS links on respective sites are removed or changed to some random link.

I think that Multisite Post Duplicator could be responsible for that, because it duplicates post meta each time you make changes in original post. There is an option to leave out some meta option from duplicatin, but I could not find where the saved language connections from MSLS are stored. Are there some mata values like this in database, or does it work some other way?

Thank you.