Formula showing duplicates in large data set

[MustaphaOj]

Hi All I would like help with making a formula that helps identify duplicates in a very large data set.
So for example the below tables shows
The end result of what I would ideally want the error check to look like. If I have duplicates of the same code and activity name together I’d like it to show in the next column. Thanks in advance

Activity ID	Activity Name	Duplicates
12344	Plates	3
12344	Plates	3
12355	Spoons	0
12344	Plates	3

 

[Peter_SSs]

Could you use something like this, with 1 meaning no duplicates?
Not sure how big your data is so there could be a performance issue?

20 07 13.xlsm
	A	B	C
1	Activity ID	Activity Name	Duplicates
2	12344	Plates	3
3	12344	Plates	3
4	12355	Spoons	1
5	12344	Plates	3
Dupes

Cell Formulas
Range	Formula
C2:C5	C2	=COUNTIFS(A$2:A$10,A2,B$2:B$10,B2)

If you really need the zero, then the following but it significantly increases the processing required.
=IF(COUNTIFS(A$2:A$10,A2,B$2:B$10,B2)=1,0,COUNTIFS(A$2:A$10,A2,B$2:B$10,B2))

 

[MustaphaOj]

Thank you so much. The first option works perfectly. God bless you!

 

[Peter_SSs]

You are very welcome. Glad it worked for you. Thanks for letting us know.