Basically, the characters are cloned and transferred from the moment they end, in this case, it would be like this, minutes before Springtrap dies in the fire, Golden Freddy copies his essence and personality and makes him be in the UCN, or in FNAF 6 itself, he would do something similar to puppet and the fact that SpringTrap attacks, is because this SpringTrap (obviously not the original) is being manipulated by Golden Freddy, and in all of them it is like this, he manipulates but still maintains the copy of each one's essence