Unfortunately, the issue is still present with 2.0.x version, and #18 (adding Content ID after Date solves it).
Steps to reproduce (in my case):
1. Create 50-100 nodes of a specific content type for testing;
2. Create 6 or more nodes with the same published date;
3. Create a view to display the teasers of this content type;
4. Sort them by "Content: Date Posted";
5. Add "Infinity Scroll" pager with a specific number of items to display (in my case 9);
6. When I have 6 or more teasers with the same published date on the page ( e.g.: 4 or 5 are visible and the 6th will be added on the next "load more") and one or more of them are located in the next 9 items that will be displayed, after clicking the "Load more" button, one of the teasers is duplicated and it's present in the next 9 items that are added.