[TYPO3-project-seminars] Duplicate Registrations?

[Peter A. Schott]

Running TYPO3 4.2.6, latest release of Seminars, on MySQL 4.x and PHP 5. I
have plenty of memory allocated as far as I can tell and am using the
onetimeaccount extension for people who do not want to create an account on
the site.

I used this setup last year with no major problems, but for some reason this
year I see many people register who then have duplicate (triplicate,
quadruplicate) registrations instead of the one entry they are expecting. I
can clear them out in the back-end easily enough, but they receive multiple
confirmation messages, multiple Seat IDs, and it's pretty confusing to them.
As far as I can tell, they aren't re-submitting their registrations, but I
can't say that for sure.

Any ideas on what I can check or try to prevent these duplicate registrations?
It all works, but it definitely looks unprofessional.

Thanks for your time and help.

-Peter Schott