This bug was reported for the Simplex2 portlet (the old version) but may also apply to the revised version (Simplex3). Submission of one job works fine but the second job throws a big error, probably a database lock problem.
I also have seen a database lock problem often for a long time, I'll look at the code working with the database.
I also have seen a database lock problem often for a long time, I'll look at the code working with the database.