It has always been a problem with copying data from one SQL DDL table to another if the table contains an identity column. Identity columns are controlled by the database itself. When a new row is inserted into the table the database assigns the Identity column in the new row the next sequence number. They are a great way to ensure that the table has a unique key, and they can be shared with other files as an external key to link back to the original table.
The issue has always been that if I copy data from one table to another with an Identity column of the same name the database will assign the inserted rows new identity values using the sequence of the copied to table. This has been a great frustration to us all, and has led to many forsaking Identity columns altogether.
