[U-Boot] question regarding the odroidc2 board support

Greetings,

I'm using buildroot to generate images for the odroid c2 boards and from what I see, it uses u-boot.bin to burn into the image. I'm not seeing any other uboot product that is used for booting (unless I'm mistaken). I'm reading the odroid c2 readme file and I see it instructs the use to burn a alternative u-boot.bin from the one that was created by the env. I wonder how it is possible to actually use newer uboot when in the end uboot recommends to replace u-boot.bin with pre existing one?

Thanks,

Dagg.