Preventing multiple users from using the same login

I was just asking the same question. The best way I can think of is to remove the "user-sign-up" and get people to sign-up using their facebook account. They don't want to share this account as it's a lot more personal, and it's actually easier to use than the normal sign-up page (and better for mobile users as no typing)

Hi Tim, Thanks for writing. That's actually a simple solution that I'll keep in mind for some other sites. It is not suitable for this particular client because less than half of this particular client's users are FB users (believe it or not) so it would be best (in this case) if the solution were part of CMSB. There should be a way to control this...by an off/on string inside the membership module or on the php pages that interact with the membership module...or something.

Hi Jason. That is absolutely correct. I'll submit a bid request as you suggested. Thank you.