Is that really the best idea?  Or should you simply add a Quantity
column to your table? Duplicating records should not even be possible
in well-designed databases. Think about it: what if I duplicated some
Product records, and then in another part of the application I have a
dropdown list to select a Product. The user would see what appears to
be the same product twice. He's rounding up a posse and is going after
you with tar and feathers. This is getting ugly...

-Tom.