You can use three methods to identify your respondents:
Identify question
The simplest method of identifying the fillers is adding a question in the form the person is filling out to enter data that will allow you to identify him. These can be personal data and a unique code provided to this person.
E-mail invitations
Using this method, we send e-mail invitations to the e-mail addresses added to the system. When the "Form available only for e-mail invitations" option is enabled in the Settings, it is possible to enter the form only using such a link from the invitation. The link is valid for one completion, and after being filled in, it binds the reply to the e-mail address to which sent the invitations.
It is possible not to reply to the e-mail address. In this case, deselect the "Track recipient responses" option when sending invitations.
Hidden variables
The third option is Hidden Variables (Settings- Hidden Variables). Hidden variables allow you to add a variable to the form, which is saved together with the given answer. You can use such a variable to identify respondents and eliminate duplicates.
