There is a text with a mix of Arabic and ASCII characters (attached), and it is
displayed correctly (first screenshot a.k.a top.png). But, when I concatenate
this text with itself (cat /tmp/uthmani.txt /tmp/uthmani.txt > 1.txt) and view
the result, second Arabic fragment is rendered L2R (second screenshot a.k.a
next.png). Why it is different from the first Arabic fragment, and isn't it a bug?

Dmitry