found a problem in database with special signup form and limit records (add a record when signing up). i discovered that the mod doesn't check for duplicate record id when using special signup form.
solution:
change:
if ($in{'add_record'}) { # don't need to worry about duplicate key if modifying
to
if ($in{'add_record'} || $in{'signup'}) { # don't need to worry about duplicate key if modifying
solution:
change:
if ($in{'add_record'}) { # don't need to worry about duplicate key if modifying
to
if ($in{'add_record'} || $in{'signup'}) { # don't need to worry about duplicate key if modifying