Mixing different colors of antifreeze should not be done since when you mix different colors of antifreeze such as the orange and yellow antifreeze the antifreeze turns into a gel like substance.
Then that gel like substance will clog your radiator and coolant system and lead to overheating of the engine.
Now you can mix different brands of antifreeze if needed as long as the antifreeze is the same color such as green or orange.
If your antifreeze in your vehicle is green then you need to always use green antifreeze and if your antifreeze color in your vehicle is orange you need to use orange antifreeze.
Never mix the colors of antifreeze or your engine will be harmed but you can mix different brands of antifreeze as long as they are the same color.