The feature was designed to poplulate ALL pages with the Master page content, hence the name, Master page. If you want to remove the Master page from certain pages, select that page, and then in the Layers panel choose Remove Master Page Layer from the Layer options.
You might also want to take a look at the "Share layer to pages" functionality (in the right side menu of the layers panel). That will allow you to share a layer across some pages but not others. I use it more often than master pages nowadays