Comment 26 for bug 209145

I am not sure why wlx can display both correctly.
I think the difference that one works and one doesn't is exactly equivalent to the upstream bug. <https://bugs.freedesktop.org/show_bug.cgi?id=15301>

Even a person who doesn't know Chinese is likely to tell the difference.
* <http://bugs.freedesktop.org/attachment.cgi?id=16318>
* <http://bugs.freedesktop.org/attachment.cgi?id=16319>

I noticed more people experiencing the same problem.
* <http://linuxdesktop.cn/2007/11/27/xpdf.html>
* <http://www.linuxsir.org/bbs/thread259224.html>

Comment 8 in the link has probably a correct diagnosis of the problem, pending to be fixed by upstream.
Using xpdf instead or recompiling poppler with splash backend seems to be workarounds.