In the graph plotting question, it is easy for authors or students to plot duplicate shapes on top of each other without realising. It is impossible to tell if there are duplicate shapes from a pure visual inspection. Duplicate shapes can cause validation to fail if the Ignore repeated Shapes option is not switched on.
To avoid this issue, authors can use the Ignore Repeated Shapes flag. This can be found in Validation.
Figure 1: Ignore repeated shapes drop down menu in the Question Editor.
The possible options are:
