Doubt about conversions brake-fork

Hello! I've always had a doubt when make conversions from single brake disk to two. Its not necesary make something with the fork? New spring? New oil? Nothing? You can put other disk and the fork will work well? Both bottles of the fork ....have the same hardness?
Thank you!

You don't really have to change anything else except usually fit a bigger master cylinder.
You just get to stop quicker.

One thing to consider is that to minimize unsprung weight the rotors on the dual disk systems were thinner (lighter) than those on the single disk systems. So if you decide to make a dual disk system be sure both rotors are the same thickness. Ed

Some dual disk brake rotors are smaller in diameter than the single disk, so you have to be aware of that >> the dual disk brake calipers will be lower on the fork legs. But I'm guessing your RH fork already has a brake caliper mount, so this may not be an issue with your bike, whatever it is.

ps: It helps to mention the motorcycle, although for comparing stuff, non-USA & non-Canadian models may not be listed in the available diagrams.

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Thank you everyone. I'm going to dive in the forum and come back again plenty of doubts!