are rear surround sound speakers having same sound

My understanding of Logic 7, when used with a 5.1 source and driving a 7.1 speaker array for example, is it will process the two surround channels and make a determination of where to send the surround information. It reallocates the surround information across four surround speakers rather than two, depending on where it thinks the audio engineer wants the sound to emanate, to provide 7.1 discrete outputs. This allocation is dynamic, depending on signal content.

I do not know how DPLIIx works, but my guess is it's a similar concept to Logic 7 but with a different algorithm.

Thanks
Bruce

Very nice when you hear clear surround sound. By the way, I saw a system that sounds good. https://geeklah.com/best-wireless-surround-sound-system.html

7.1 source material.

https://www.youtube.com/watch?v=qHcZfzwmEbs
You may need forego using the above youtube link and go directly its address. 

https://forum.blu-ray.com/showthread.php?t=159814