menu.xml.it and xfce-registered-categories.xml.it have their contents duplicated and indeed seem to have had this for a while, however in xfdesktop on 4.4.1 in a current Debian unstable environment this makes xfdesktop segfault. I have gtk 2.10.11 and glib 2.12.11. To reproduce try export LANG=it_IT.UTF-8 (and generate that locale if you don't have it) and then run xfdesktop. I'll attach my --enable-debug build logs given that. Removing the second copy papers over this bug. I'm not sure where in the code this fails and didn't dig any deeper but I'm sure you'll want to.
Created attachment 1107 Output from a crashing xfdesktop built with --enable-debug
Created attachment 1108 Output from GDB running the crashing xfdesktop (same time as the debug.log above)
The XML parser probably doesn't validate the XML well enough. I'll take a look.
Not going to bother... shouldn't run into this in normal cases, and this stuff will disappear in 4.6 anyway.