The tables of the projects din_15413_a.prj and din_15413_b.prj have been merged in one project din_15413.prj.
In order to create the mapping proceed as follows:
Initial situation: Select the first project to be merged. In the dialog the target project's table is missing.
Repeat the procedure for the second project.
-> Once selecting a row in the left table, on the right, the correct target project is shown.
Verify the assignments by clicking on Confirm all assignments [Verify all mappings]
the assignments.