Loading contract history using HDL is adding additional rows in assignment table

Summary:

I am trying to load a non worker data with its contract history information using HDL. While doing so since the workterms and assignments are part of the contract HDL (with action code contract_extension), the same is inserted as a row in the assignment table per_all_assignments_m.

But while doing the contractor extension via application no such row is inserted

Can anyone help on how to load the contract history details without affecting the assignment table

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