Multiple sections in Theme Customizer overwritten

In order to create a section, it must have a control, and each control requires a unique control id, you are passing the same control id image to both of your controls and hence it will create a control for the last one, and ignore the previous one. Therefore your first section does not get any control and it is being overridden.
In short you need to pass unique control ids to your controls inside WP_Customize_Image_Control.