I’ve tested Single layer and double layer from the same movie on the same LG C7 and 65” C9 and there is no difference, obvs both are mp4, mp4 is just a transport for the streams.
I think people are getting overly hung up over this, dual layer is interleaved into a single watchable item inside the TV, where in a single layer the the enhancement layer is already interleaved. One requires hardware (double layer) one can be done in pure processing power(single layer)
If Single layer was inferior LG would be lording it over all those Sony’s TVs that only accept single layer wouldn’t they?