Pull random 10 entries without duplicating every time when ajax calls

Possible to pull random 10 entries (without duplicating entries) with ajax everytime when scroll to the bottom, right now it loads random 10 entires but it duplicates and some entries never shows up. Any ideas? thanks

index.html:

{exp:channel:entries channel="channel_A|channel_B|channel_C" orderby="random" limit="10"}
  {content}
{/exp:channel:entries}

ajax/index.html

{exp:channel:entries channel="channel_A|channel_B|channel_C" orderby="random" limit="10"}
  {content}

  {paginate}
    {pagination_links}
      <ul class="lepaginate">
        {page}
          <li><a href="{pagination_url}" class="page-{pagination_page_number} {if current_page}active{/if}">{pagination_page_number}</a></li>
        {/page}
      </ul>
    {/pagination_links}
  {/paginate}

{/exp:channel:entries}

jquery:

  var counter = 10;

  $(window).scroll(function() {
    if($(window).scrollTop() + $(window).height() == $(document).height()) {


        var response;
        $.ajax({ type: "GET",   
          url: ""+document.location.origin+"/ajax/P"+counter+"",
          async: false,
          success : function(text) {
            response = text;
          }
        });

        counter += 10 ;
        newItems = $(response).appendTo('.grid');
        $grid.isotope('appended', newItems );


          var $grid = $('.grid').isotope({
            masonry: {
              columnWidth: 360,
              gutter: 30
            }
          });

    }

  });

this is using pagination, so it loads like '/ajax/P10' '/ajax/P20' ..., etc