Can I check in at two hotels at the same time with my ID card?

No, accommodation registration requires one ID card per person to check in.

According to Article 56 of the "Public Security Administration Punishment Law of the People's Republic of China": If hotel staff do not register the name, identity document type and number of the accommodation passengers as required, they will be punished. Or if a guest knowingly brings dangerous substances into the hotel and fails to stop them, a fine of not less than 200 yuan but not more than 500 yuan will be imposed.

If a staff member of the hotel industry knowingly knows that the guest staying is a criminal suspect or a person wanted by the public security organ and fails to report it to the public security organ, he or she shall be fined not less than 200 yuan but not more than 500 yuan; if the circumstances are serious, he or she shall be fined not less than 500 yuan but not more than 500 yuan. Detention for less than 50 days and a fine of not more than 500 yuan may be imposed.

So accommodation registration can only be for one person and one identity, and you cannot check into two hotels.

Extended information

The "Hotel Industry Public Security Management Measures" stipulates:

Article 6: Hotels must register for accommodation of tourists. When registering, the passenger's identity document shall be checked and the passenger's identity document shall be truthfully registered according to the prescribed items. When hosting overseas tourists for accommodation, they must also submit an accommodation registration form to the local public security agency within 24 hours.

Article 7: Hotels should set up safe deposit boxes, cabinets, storage rooms, and safes for passengers’ belongings, and designate dedicated personnel to be responsible for safekeeping. A system for registration, collection and handover of property deposited by passengers must be established.

Article 8 Hotels shall properly keep items left by tourists and try to return them to their original owners or publicly claim them; if no one claims them after 3 months of recovery, they must register them and send them to the local public security organ for press release. Disposal of found items. Prohibited items and suspicious items should be reported to the public security organs for processing in a timely manner.

Reference materials: Baidu Encyclopedia - Public Security Management Punishment Law of the People's Republic of China

Reference materials: Baidu Encyclopedia - Public Security Management Measures for the Hotel Industry