Legal analysis: as long as it can be proved that the electronic signature has been tampered with after its formation, or that the previous signature has been copied into the subsequent contract, it can be considered invalid.

Legal basis: People's Republic of China (PRC) Electronic Signature Law.

Thirteenth electronic signatures meet the following conditions at the same time, as reliable:

(1) When the electronic signature production data is used for electronic signature, it belongs to the exclusive rights of the electronic signer;

(2) When signing, the electronic signature production data is only controlled by the electronic signer;

(3) Any changes to the electronic signature after signature can be found;

(4) Any changes to the content and form of the data message after signature can be found.

The parties can also choose to use electronic signatures that meet their agreed reliable conditions.

Article 14 A reliable electronic signature has the same legal effect as a handwritten signature or seal.