Dup Key with SQL Server getdate()

I am using Visual Basic 6.0 and SQL Server 7.0, both with the latest service packs. The user types in a number and presses enter.
Using ADO, I then perform an insert into a table that has the number entered by the user and a datetime field as the key. Inserted is the number and getdate(). How is it possible that I am getting duplication keys??? This exact application worked in SQL 6.5!!! I know I have a fast computer, but hand keying the number pressing enter, and two separate calls to the database that both return the exact same millisecond is not feasible. Is there some new sort of buffering is SQL Server 7.0? Any ideas???