Duplicate columns with Pandas merge?
<p>I have a data frame <code>a</code>:</p>

<pre><code>ID    value1
1     nan
2     nan
3     nan
4     nan
5     nan
</code></pre>

<p>and then two other data frames, <code>b</code> and <code>c</code>:</p>

<pre><code>ID     value1
2      20
3      10

ID     value1
1      58
4      20
</code></pre>

<p>When I do <code>a.merge(b, on='ID').merge(c, on='ID')</code>, I get duplicate columns of <code>value</code>. My end result has the columns:</p>

<pre><code>ID     value1_x    value1_y    value1
</code></pre>

<p>but I want to end up with:</p>

<pre><code>ID    value1
1     58
2     20
3     10
4     20
5     nan
</code></pre>

<p>How do I use <code>b</code> and <code>c</code> to populate the values in <code>a</code> without duplicate columns?</p>