When (or how) are database logids reset (to zero or one etc) ?

Reading our db log files (which span many days) we keep coming up
against a message that indicates that duplicate logids have been found.
My guess is, that because we keep the same log file cycle for many days
(we only use them for traceability), the logid is being reset at some
point and then starts over at zero or one thus duplicating itself.

Thank you as always.

Costas Anastassiades,
Intracom SA
Athens - Greece