You have sharp eyes.
The two on the top were created a bit differently . It was more of a hit or miss experimental process from me than the one on my mini-tutorial, and I thought nobody would notice. You could modify the shape of the intersected piece before duplicate-rotating it, though and you'll end up with something similar.
What I did was to create an polygon with the desired number of corners (choose the polygon, not the star alternative and hold down the Ctrl key so you could drag out a regular polygon). With the quick shape still selected, hold down the ctrl key and drag the control node inwards so that you create a multipoint star. http://www.corel.com/servlet/Satelli.../1161192409839
Convert the shape to a regular path. With the node editor, select all nodes, convert the edges from straight to curved. You will not notice any change in the shape after this operation because the nodes are all cusp nodes. Now select all the nodes at the spikes of the star (drag-select, shift select or click the select all nodes button) and convert the node type from cusp to symmetrical. You will now have a star with fat rounded points. The nodes on the spikes should remain selected at this point. Convert these nodes back to cusp nodes again. The star's shape should not have any visible change. Select all nodes again and press the add node button. New nodes will be added to the sides of the spikes. With all nodes still selected, convert the curved edges back to straight edges ( are you still with me?) then convert to curved edges, again.... Then finally, select the nodes created with the add node button and delete them. That should give you the final result...
Now you know why I didn't do a tutorial on that process...