As long as the contract is the true intention of both parties and does not violate the prohibitive provisions of the law, it will take effect after being signed by both parties. As for the number of copies signed, it has nothing to do with validity and invalidity, but the original is the formal proof of the contractual relationship, and the copy cannot prove the contractual relationship alone. The difference is only the validity of the evidence, not the validity and invalidity of the contract.
People's Republic of China (PRC) labor contract law
Article 16 A labor contract shall come into effect after the employer and the employee reach an agreement through consultation and sign or seal the text of the labor contract.
The text of the labor contract is held by the employer and the employee respectively.