WebEx creating duplicate attendees?

Hello all!

I'm having an issue with WebEx I can't seem to figure out...

I have setup the member URL successfully for the user to click on to join the webinar. The problem is, when they land on the page to join, they have to input their first/last name & email. If they use the same email as they registered with, it works fine, but sometimes users will use an alias that is different than they registered with (i.e. jsmith@company.com vs john.smith@company.com). This sends them through the registration process on WebEx, which they complete and then join the webinar. The problem now is that WebEx records 2 different registrations for the same person; the first one of which get's recorded as a no-show. The second one then gets imported into Marketo as a new lead which is a duplicate of the one who registered with the different email address.

It seems like all of this could be solved by simply pre-filling the user's email address when the click the link to join. I have searched up and down both Marketo community and WebEx help and this doesn't seem to be addressed anywhere. I'm probably missing a setting somewhere.

Has anyone else experienced this before, and if so, any solutions or workarounds?

Thanks!!