Comment 5 for bug 1039375

http://ubuntuforums.org/showpost.php?p=12219784&postcount=7

"As it turns out the very next release of gvfs produces the duped icons - gvfs_1.13.4-0ubuntu1

It is a 'new upstream' release so nothing too visible in the change log.
Could turn out that the various Fm dev's will have to adjust or maybe something in gvfs though it doesn't occur in nautilus (not unexpected

Edit: worth noting that the bug Elfy files was on 08/21 which certainly predates the upgrade to 1.13.4 on 09/02 so thunar may have other issues than seen here with pcmanfm

Re-edit
While installing/running thunar on my install can't totally reflect a Xubuntu install, (thunar seems confused as to my theme, ect. & running it in gnome) see single sidebar items with 1.13.3 & doubled with 1.13.4
This is with the current udisks2 packages"