[GenSec]

Forget P_polloption.
Just create new template with name P_polloption_mult:

<tr>
  <td bgcolor="{secondaltcolor}" width="5%"><input type="checkbox" name="allvotes[$P_option[number]]" value="yes"></td>
  <td bgcolor="{secondaltcolor}" colspan="3"><smallfont>$P_option[question]</smallfont></td>
</tr>

Then take on your local comp dir with your files.php for portal and look for one that has line

eval("\$P_pollbits .= \"".gettemplate("P_polloption")."\";");

.
It's not in templates.