solve bug duplicate column

src/INSATab.php

@@ -99,6 +99,9 @@ class INSATab extends ACMEWebComponent
 
                 $headerBuilder .= $this->openTag($th, $key, $key) . $key . $this->closeTag($key);
 
+                $i++;
+                continue;
+
             }
 
             $headerBuilder .= $this->openTag($th, $key) . $key . $this->closeTag($key);