title: Why is it returning a warning when reshaping in R?
body: <p>Here is my table that needs to be in wide format:</p>
  
  <pre><code>V1      V2        V3        V4
  1       A0      numeric   string
  1       A1         .         .
  1       A2         .         .
  1       A3         .         .
  1       A4         .         .
  1       A5         .         .
  1       A6         .         .
  1       A7         .         .
  2       A0         .         .
  2       A1         .         .
  ...     ...        .         .
  </code></pre>
  
  <p>I've been trying with something like this:</p>
  
  <pre><code>reshape(variable.name, timevar = "V2", idvar = "V1", direction = "wide")
  </code></pre>
  
  <p>Which has resulted in the following, which seems to be what I want:</p>
  
  <pre><code>V1   V3.A0     V4.A0    V3.A1     ...
  1    Numeric   String   Numeric   ...
  2    ...       ...      ...       ...
  </code></pre>
  
  <p>But I get a warning message:</p>
  
  <pre><code>Warning message:
  In reshapeWide(data, idvar = idvar, timevar = timevar, varying = varying,  :
  multiple rows match for V2 = blah: first taken
  </code></pre>
  
  <p>Why is this warning happening and how can I circumvent it? I don't want to just ignore it as I'll have to do the same for several data files. Thanks! Very grateful for the help.</p>