Adding a second subreport overwrites the first subreport file (4329711)

When adding a second subreport in the TDA Report Designer, the SQL script of the first subreport is over-written by the SQL script in the second subreport.
(The first subreport file was automatically named "DetailBand1" and when trying to put a second subreport into the report the name unfortunately stays "DetailBand1" and contains the properties of the first subreport. If changing the properties, the properties of the first subreport are overwritten.)