I have also thought about double clicking as the cause of the problem, but i am not so sure now. Prior to our last big evaluation, i have added the following to the submit button in
packages/assessment/www/assessment-section-submit.adp:
input type=button value="assessment.Submit" onclick="this.form.submit(); this.disabled=true; this.value='Verarbeitung läuft...'; return true;"
The javascript code disables the submit button and the user cannot easily submit the form twice (maybe with the return button on the keyboard). Despite this change, we had the deadlocks appearing :(
