do you mean each like is counted as two likes ? give a test user account so that someone can check it
mybb 1.6.10 supports this system?
^ check
postbit template - at the bottom if there is duplicate code then remove one
<tr style="{$post['tyl_display']}" id="tyl_{$post['pid']}">
{$post['thankyoulike_data']}
</tr>