Hello Shan Marshal,
This is the standard bevaviour of the system. If you check the pricing at Header level, you can see the list of Condition types will be posted to accounting .i.e which are considered for net value for calculation. Here you see two tax condition types seperately. Since there is a difference between these two condition types, hence these two will be posted as seperate line items in accounting.
Warm Regards
Siva B
