Eliminate duplicate values

I have attached a snapshot of a big spreadsheet to explain my query. There are duplicate customers shaded with colours (Column D) with different Asset Type (Column G). I need to have one Sales Value for each Customer. That means values in Sales (Column I) would look like those in Column J.

Is there any shortcut way to eliminate the Sales Values for duplicate Customers? I need to copy that across the big spreadsheet, a part of which is attached herewith.

Thanks for any help. Regards.

Put this formula in J2 and copy down your whole data set:

=IF(COUNTIF($D$1:$D2,$D2)=1, $I2, "")

If you want to replace the column I values, next you should:

1) Highlight column J values
2) press CTRL-C to copy
3) Click on I2
4) Select Edit > Paste Special > Values
5) Delete column J values