I have these categories and subcat
Vietnam
--VN 1
--VN 2

Paltalk
--Vietnam
--France


When I add something in /Paltak/Vietnam it is also in /Vietnam/
?? And if there is nothing in Vietnam it shows the number of files in /Paltalk/Vietnam.

SELECT d.xfid, d.filename, d.artist, d.title, d.album, d.year, d.addinfo, d.track, d.genre, d.length, d.bitrate, d.link, d.frequence, d.approved, d.weight, d.hits, d.views, t.genreid, t.genretitle FROM xoops_debaser_files d, xoops_debaser_genre t WHERE t.genreid='9' AND d.genre=t.genretitle AND d.approved = 1 ORDER BY d.xfid DESC

I think this is because of d.genre=t.genretitle

You should rename d.genre field as d.genreid and then make a request such as d.genreid=t.genreid

And now in the admin of debase if I rename /Paltak/Vietnam to /Paltalk/Vietnamese it also change Vietnam/ to /Vietnamese/ !!

You should better use ID and not category's name