Not necessarily - the clock source for logging is often at millisecond resolution, but at the speed of modern systems you could pile up quite a few log entries in a millisecond.

I handle this by having a guid field for a primary key on such tables where there isn't a naturally unique index in the shape of the data. So something is unique, and you can delete or ignore other rows relative to that. (Just don't make your guid PK clustered; I use create-date or log-date for that.)