I think you are overlooking an alternative and more probable...

I think you are overlooking an alternative and more probable explanation:
1. PTT acquires Coogee Resources in 2008-9. It is entirely possible that Coogee already owned the 20 million shares way back then and the beneficial ownership went to PTT back then.
2. In the first list showing all the Nominee entities, that shareholding I think would show up as "Coogee Resources".
3, But in the second list showing the beneficial owners that same 20 million shareholding would now show up on the list as PTT, as they are the underlying owners of Coogee Resources.
So no new ownership of STX shares by PTT. They've probably forgotten they even own them. A tiny blip on the radar way out near the horizon as far as they are concerned.
Just my own opinion. DYOR.
BTW there is no present day connection between Coogee Chemicals and Coogee Resources, as far as I can find.