I have ie, blahblah@yahoo.com and my backup is blahblah@comcast.net. Yahoo would not recognize them as having different suffixes (Yahoo and comcast.net). It would not allow me to put it in but a Yahoo tech put secondary in. Then began the month i couldn't get in and spent hours and hours on the phone. I'm a grateful person but I guess they couldn't figure it out .. 2 techs hung up on me. I figured it out and called back and asked them to delete secondary that was causing so much problems. I got a gmail.com account and called Yahoo, who had NOT deleted the one that was blocking me out, and asked them to delete the secondary acct that the system recognized as a duplicate email address .. and added my Gmail acct instead.