The requirement is to only display the first product type for each product line.
Please download report speciation for detail review. The idea is to make the < Table of Contents Entry > conditional and only add it when the product type is the first one.
Create a query item ProducttypeOrder as below
Create variable IsFirstProductType to control that the product type only shows at the first time
Unlock cell and select Product type <Table of Contents Entry> and make it use conditional render variable
Please note that Product type still display in report.