title: how to delete rows if there are duplicate values on the same row in R
body: <p>I have a data frame called <code>overlaps</code>, with columns called <code>sp_a</code> and <code>sp_b</code>. If the same species is repeated in the same row, I want to delete the whole row. Any suggestions?</p>
  
  <p>So I'm trying to delete row 3 and 4</p>
  
  <p><a href="https://i.stack.imgur.com/D392T.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/D392T.png" alt=""></a></p>