an email is automatically generated and sent to the second user.
So there are "fixed pairs" of participants?
In this case you CAN create two surveys.
The "paired" participants both get the same token in the participant table, the first gets the email of the first as an "additional attribute".
Now you create the notification mail that it contains the link to the second survey with added token.
After the first participant sumbits his answers the mail is sent to the second.#
And you merge the responses of the two surveys by token.
Joffm