XML Import fails with Oracle Constraint Violation

FAILED to import in 3.5.13 the re-exported file from 3.4.9 at customer site (see anonmyized attached export file)

-> the constraint violated is the primary key on table CONTENT (the content id!)

HISTORY:
FAILED: export of V3.3.3 did not directly import into 3.5.13
SUCCESSFUL: that same export of V3.3.3 imported successfully into 3.4.9 -> where we re-exported attached anonymized file

attached: log file snipplet with hibernate.sql logging enabled from direct import into 3.5.13 of file exported with V3.3.3