i think i know which company your talking about shabandri (ava?). From the reading I have done they also seem to be a damn good speccy play on Botswanan coal. I think both are very likely to mirror each other in SP movements for the next period of time. Aspects like sentiment, management quality, Broker support etc. could make one move more than the other, but if one goes up 200% in the next year, you would expect the other to be up at the very least 100%.
I invested in HDG just because it has a smaller market cap atm, but if I was invested in AVA sitting on a capital gain that would get taxed on selling, I would personally just hold AVA. BUT as you said, having HDG on the watchlist is smart. The low liquidity means its vulnerable to a dumping into the low 20's so it would be smart to keep a small amount of powder dry to pounce on said opportunity.
HDG Price at posting:
37.5¢ Sentiment: Buy Disclosure: Held