STP, please help on non-resident alien and resident alien joint

If non-resident elect to choose joint tax return (i.e., non-resident alien is
treated as resident-alien).
It should include world-wide income.
But if the non-resident alien is in china and
the income has been taxed in china.
Question: Does the income still need to be included in joint return?

If the answer is yes, isn't it double taxation.