When a report fulfills the following conditions :
1. Is Multicolumn;
2. Has DocumentMapText set;
3. Contains a List (data item) with DataSource set with Bindings to a field of the Report DataSource.
and is displayed in PrintPreview mode in the WPF Report Viewer, an exception like :
"Could not register named object. Cannot register duplicate name '_20aa3785775c4790ba0cfa8021bd8433' in this scope.' Line number '1' and line position '2567'. Cannot register duplicate name '_20aa3785775c4790ba0cfa8021bd8433' in this scope." is thrown.