Just thought of something else,.......
It's 'possible' that the Rhodie converted magazines were actually done later under Mugabe. It's true that Rhodesia ran both inch and metric guns but after the war I don't think the new regime contracted for anything other than Imbel metric pattern rifles. While a metric(or converted inch)magazine will 'sorta' work in a commonwealth receiver, an inch magazine will absolutely not work in a metric receiver. Perhaps it was just done to standardize or to make do. All that Rhodie stuff, kits and magazines, came in with a combination of pre-war and post-war camo colors so it's possible that the mag conversions were done post-Rhodesia.
Still, it's all conjecture based on a couple of pictures on a website that don't accurately reflect the product being sold.