I find that once in awhile (several days to month can go by) that I end up with a duplicate record.
The PrimaryKey is DATETIME in Access. What appears to be happening is
that when Access UPDATES datetime (which is a double), the time portion of the double
may be one digit larger (e.g. 9 vs 8) or one digit smaller (e.g. 7 vs 8) even though
the time is being rounded to the nearest minute. For whatever reason it then
considers this to be a different DATETIME even though when examining the database
Both records appears with the same datetime stamp.

Any suggestions appreciated.