Sample Light and Sample Switch. Why register for 2 sets of endpoint?

I am testing the Sample Light and Sample Switch project. I have a question on the afRegister function. I realize that the zclSampleSw_Init function call the zclHA_Init function. In fact the zclHA_Init function will call the adRegister function to register for SAMPLESW_ENDPOINT(10).

On top of that the zclSampleSw_Init function will also call the adRegister function and register another endpoint sampleSw_TestEp which is endpoint 20. I am confused here. Why we need another endpoint 20 for this application example

Thanks