Hi
This may happens because the document has same layout between pages and DU getting as multiple pages of the same document type. For exame, a PDF that contain 10 invoices.
You need improve your classifier, but if pages has the same layout its a little difficult. You have option to use Keyword Based Classifier
Or you can check in Classification Rules Check if the classified document has the same quantity of pages of the original ones:
in_ClassificationResults(0).DocumentBounds.PageCount, StartPage etc. Based the result , even classifier gets divide classifications, you send to manual action to human fix it before continue to Extraction Flow
In the new update of document understanding we will have option to disable splitting in classifier, see here: