how to remove duplicates with the earliest date ?

One way ..
Insert 2 new cols A and B
(ICAP ID is now col C, completion_dt = col G)

Put in B2, array enter (press CTRL+SHIFT+ENTER to confirm the formula):
=MIN(IF($C$2:$C$100=C2,$G$2:$G$100))
Copy down. Modify the $100 bit to suit the extent of your data
This col extracts the earliest completion date for each ICAP ID

Put in A2:
=IF(C2="","",IF(SUMPRODUCT((C$2:C2=C2)*(B$2:B2=B2))>1,"x",""))
Copy down to the last row of data, this will flag dups as x based on your dual criteria
Filter on col A for x, delete these filtered rows, remove filter, delete away cols A and B > you're done !
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voila? Wave it, click the little star at the bottom left of my responses

Sort by ICAP_ID, Completion date, then use the built in duplicate remover. Excel only keeps the top unique record in the list.