I have the X2 Student type when coming to China from Denmark,

and I have extended my Visa time here in China. Back when I was in Denmark, the CVASC made a mistake and gave me single entry rather than multiple entries even though I checked multiple entries on my visa paper. Here on me extended visa in China, I still have single entry. But since I already am in China, does that mean that I can go to Korea and back to China again without applying for a new visa?