This is because you have the option to show the section lists above and below any products that you might show on this page. There are two variables being used:
SubSectionListTop
SubSectionListBottom
To only show one of them you need to set the other to 'No Layout'. If you want this to be the default then set it in 'Settings | Site options | Layout tab | Section group' - you need to set 'Bottom Subsection List Layout' or 'Top Subsection List Layout' to 'No Layout'. Alternatively, you can apply it only to particular sections by setting it in the 'layout' tab of the section details.