The article framebuffer integration and double-buffering describes the different possible integration scenarios that can be used or that might be useful for several reasons.
In case of OpenGL ES 2.0 the entire framebuffer integration and the aspect double-buffering is managed by EGL. This means, EGL allocates and manages the framebuffer and takes care for the update (swapping) of the framebuffers.
Please check the settings of your EGL initialization - from Embedded Wizard side there are no settings that will change or control the EGL framebuffer behaviour.
Maybe the return values from the EGL initialization functions will help to find the reason.