Since a few Reader releases you need to use the Extended Page Sequence function to make pages not visible or adding a fake page in double mode. If you open that function (click on the page sequence symbol) the help will come up on how to use that function, it has not been  included in the manual.

For now the fake page will be added to the right of a given page , in the next release it will be available on the left as well.

Hence for now if you need to add a fake page on the left tablet, here is the trick : create a group of just one page using the very first page of the score in order to have it duplicated , in this way your score starts as shifted to the right.