Layers in Object Manager

This is more out of curiosity than anything, but could somebody explain what's happened here. This is how pages in a typical I work with look in Object Manager -


Page 5-6 shows two paras bundled on Layer 3 (side by side on the page) with a redundant Layer 3. Page 7-8 show two separate paras on Layer 1 with no redundant layer. I've been creating new documents from previous ones to keep the format and extended them by the usual method of adding a page [+], clicking on the bottom of the text frame on the previous page then clicking on the new page. I've tried to recreate the separate paras as in Page 7-8 by this method but can't. Only by dragging them around in Object Manager can I do it. I'm just curious how they came about this way. As you may gather, I'm not familiar with Layers!