Constraint violations with MVLOCKS

Hi,

I'm getting intermittent PK constraint violations on sql updates when
switching from LOCKS to MVLOCKS, even if the update doesn't touch any
PK column (and it works with LOCKS): are there any known bugs/issues
with MVLOCKS maybe?

I'm using HSQLDB 2.2.9, and I could privately provide a sample
database where to reproduce the issue.

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