Excel formula

Hello all,

Could someone please help me

I have 2 data tabs of 000s of horizontal data fields and probably 30 columns each tab

first tab is a carrier shipping, the other dispatched tab, the common is the order number. 

I have used vlookup to import shipping cost to the dispatched tab, the unfortunate problem i now need to find a solution for is for many orders there are multiple lines of different products which now records the shipping cost to every line excellerating the cost. How do i in these cases only record the shipping cost once on the first line of the order

Unfortunately I am unable to remove duplicates as this would mean deleting the record of despatched products. Any help or guidance would be greatly appreciated.

Many thanks

Mark