Two Recipients One E-mail Using KBA

I have a client and spouse that only have one e-mail address. We use KBA for authentication. We listed the e-mail twice and requested that each one click on the link, input their individual information, but when it was received back (signed), the client signature was correct and the name printed below was correct but the spouse had the correct signature but the name listed below the signature was not the spouse (it was the client).  Why would this have happened?