Its Small seal script is
Let's compare it with bronze script for One
It is clear that the Pair is one hand holding two birds, and the One is one hand holding one bird.
The clerical script for Pair is
similar to its samll script, but the the bottom for hand changes to a symtric, less pictography.
The current standard printing script for traditional character is
very similar to its clerical script.
The current standard script for simplified character is
The two birds disappeared, but there are two hands. Well, two hand may be OK to represent "Pair", however, the change is a little bit disconnected from the older scripts, at the same time, it is too similar to another character "Friend" (Post 103)
which is evolved from two right hands, let's see its samll seal script
which is the original "two hands", not the "Pair". So I would say that the simplified character for "Pair" is not good simplifying.
Its Pinyin is "Shuang1".