Do we need “about” in “Employees are unhappy with about low wages”?
Solution 1:
It looks like a simple mistake. Writer originally wrote with, and changed it to about, but forgot to delete the unwanted word.
Disregarding whether that conjecture is actually what happened, there's no question but that using both words is incorrect. As music2myear says, there are semantic/grammatic reasons for preferring about; it may be these are what caused the writer to change his wording. However, it's worth pointing out that over the last 100 years there has been a significant shift in favour of with...