Assign your toc grid a unique ID:
<div id="theTOC" class="ui-grid-b"></div>
Then in your code instead of:
$(".ui-grid-b").empty().append(toc);
do
$("#theTOC").empty().append(toc);
Make sure this id is unique accross all pages. Also make sure your pages have unique IDs (i.e. only one page called "Page1").