I have two databases (SQL Server 2005) with the same table schemes. I need to copy data from source table to destination with some modification of data along the way.

And if destination table already contains some data, then rows from source table should not override, but be added to the destination table.

In our project we use LLBLGen and LINQ to LLBLGen to as ORM solution.

Example:

Table 1:          Table 2:                     Table 1:
Key Value         Key Value                    Key Value
1   One           1   T2_One       Result=>    1   One
2   Two           2   T2_Two                   2   Two
3   Three                                      3   Three
                                               4   T2_One
                                               5   T2_Two