Adobe Acrobat error during signing documents

Adobe Acrobat error
We use Adobe Sign to approve important documents. Each signer has created an Adobe account, created the necessary signatures and settings.
When a document is included in the signing round, notifications are sequentially generated to each participant about the need for their interaction during the e-signing process. The notifications arrive via email and include a "Check and Sign" link to an authorized page where the user simply clicks on the necessary fields and the signatures are automatically applied. There is no need on his part to authenticate during this process.
The problem arises when one of the signers FORWARDS his email with the link to someone else. If the next recipient clicks on the "Check and Sign" link, they are taken to the same page as the notified user and are able to sign the document with the signature of the originally notified person!
The subsequent signature notification comes on behalf of the original user who was prompted to sign the document. Even from the signature audit it is not obvious that an unauthorized signature has occurred.
This situation occurs if no additional authentication method is chosen for signing (password, email+password), only email authentication.