When an addon defines a panel for the toolbar it should add a property called
bl_category which defines the name of the tab it will be shown in. If this property is not defined then the panel will be shown in every toolbar tab.
Current repository versions of Contours and Oscurart Tools have been updated to have their own tabs. Contours was updated in January and Oscurart Tools in February. The solution for these would be to update them.
'''Retopologize Forms with Contour Strokes'''
bl_category = "Retopology"
bl_label = "Contour Retopolgy"
bl_space_type = 'VIEW_3D'
bl_region_type = 'TOOLS'
I don't know which addon Object Tools belongs to. To manually fix this edit it's source file by right-clicking on one of it's buttons and select Edit Source. Then add a
bl_category property to the panel. If this addon is located within the official addons or addons_contrib then you will need to repeat this when you upgrade, if the addon still hasn't been updated. If it is an official addon or from addon_contrib them submit a bug report (include a patch?) to get it updated.