Fix fontforge#117 BuildDuplicate used two encoding points.

Author: nickaugeo

docs/scripting/scripting-alpha.html

@@ -418,7 +418,7 @@ <h1>Scripting functions<a class="headerlink" href="#scripting-functions" title="
 <dl class="ff function">
 <dt id="BuildDuplicate">
 <code class="sig-name descname">BuildDuplicate</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#BuildDuplicate" title="Permalink to this definition">¶</a></dt>
-<dd><p>Changes the encoding so that to encoding points share the same glyph.</p>
+<dd><p>Changes the encoding so that two encoding points share the same glyph.</p>
 </dd></dl>
 
 <dl class="ff function">