First off, they arent even that similar. Freeza has his chest and shoulders covered in bio armor ontop of having pink skin not this weird shade of purple
king cold also has a spiked tail where freeza has a normal tail.
Second off, Freeza's forms arent racially inherited
He created them to suppress his power meaning king cold would not have this second form plus narratively it makes no sense why not use his additional forms versus trunks if he has them, you saying that he let himself die for fun?
Freeza stated, he can make forms as he wants as seen with how he made golden freeza, golden as a means to spite goku so could stand to reason that he did the same with his dad what do i know
