You need to buy two springs (1) the other will snap as well (2) the other will sit lower than the new one.
It seems that there is (1) standard suspension (2) sport suspension (3) self levelling suspension.
So there are three part numbers.
https://www.autopartspro.co.uk/sachs-1231606https://www.autopartspro.co.uk/kilen-7837043Compare the different part numbers.
I would not buy before I was sure that will fit.
https://www.onlinecarparts.co.uk/car-brands/spare-parts-mazda/6-hatchback-gg/19107/10213/coil-springs.html?criteria%5B100%5D=HAI think all of them are the same in terms of compatibility. But I have no idea why the same part has multiple oem part numbers.
Can you try emailing them?
And also email different Mazda traders and compare notes?
I think it is one of those things that you will not be safe with a single answer but when you seek multiple opinions you will get more confused. It is more likely to be told, that will do, let's crack on.
But in theory at least there should be some difference but I am not sure who would have such knowledge.
I check my GH car at
https://www.onlinecarparts.co.uk and it also returns three different part numbers and I can see (1) standard suspension (2) sport suspension (3) constant wire coil sping
I think the same happens with your GG car as well (1) standard (2) sport (3) variable wire it calls it.
There are £25 each plus postage. So you will better confirming before buying anything.