excel mark duplicates values

I have a data like this:

input:
person1     9
person1     8
person1     8
person2     7
person2     8
person3     6
person3     8
person3     6

output this:
person1     9   no
person1     8   yes
person1     8   yes
person2     7   no
person2     8   no
person3     6   yes
pe开发者_高级运维rson3     8   no
person3     6   yes

I am using excel and i want to use an if condition to determine when a person have two same values. How can i do this for the whole sheet?

thanks.

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It is an easy two step formula

• Make a working column that combines the strings from your two columns, ie if they are in A&B then in C1 put =A1&"-"&B1

The "-" helps avoid false matches

• in D1 enter =IF(COUNTIF($C$1:$C$8,C1)>1,"yes","no") and copy down