deleting rows provisionally

I have an object. I think it is a matrix, called 'answer2'
 str(answer2)
 int [1:1537, 1:2] 1 399 653 2 3 600 4 5 271 870 ...
 - attr(*, "dimnames")=List of 2
  ..$ : chr [1:1537] "a4.1" "hirschsprung.399" "peritoneal.653" "abdomen.2"
...
  ..$ : chr [1:2] "row" "col"


I want to delete rows that have the same entries.
For example:

answer2[4,1]

[1] 2

answer2[4,2]

[1] 2

And so I would like to delete row 4.

I tried the following but it does not work.
I defined answer3 to hold the result by first:

answer3<-answer2

and then:

for(i in 1:1537){if(answer2[i,1]==answer2[i,2]){answer3[-i,]}}

Why doesn't this work?
Thanks.

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