List unmatched items in 3rd column & sum matched items in 4th column

Hello - first post and never programmed a macro.

I have different words in the 1st column and numbers in the 2nd column. I need to list the unmatched words into the 3rd column (only once) and sum the matching numbers into the 4th column.

A B C D
1 adac900 100 adac900 140
2 dsal300 50 dsal300 66
3 adac900 40 dsbl600 20
4 dsbl600 20 cbwd 43
5 cbwd 33 adac600 15
6 adac600 15
7 dsal300 16
8 cbwd 10

Any help would be oh-so-most-greatly appreciated. My brain is on overload reading the different posts and applying their answers to my problem. Best regards, Sharon.

Now I'm a chishire cat too because I'm grinning from ear to ear! Thank you so so much. We've been talking & working on this for weeks & in no time at all you figure it out! I can't tell you how much work this will save me. I will mark this as solved. If I can help you with something Please don't hesitate to let me know.