Philips SBC 42 g Audio Signals Disc

I have had a Email from Miroslaw , he got this copy of a SBC 42 g  , I know the SBC 429 , but  is this a different version..?

“I have never heard of the SBC42g. Its content is very similar to the SBC429. For example, I noticed that tracks 66 – 73 are the same, but the signal appears not in the left channel (as the SBC429 specification shows), but in the right channel. “

Does anyone have more information off this SBC 42 g version..?

My copy SBC 429

Update : 2025-05-04

“Thank you very much for your help. After analyzing the contents of this CD, I can say that it is similar to SBC429.  It is probably its earlier version.”

SBC42g 

SBC429