Those who fought HKs were Rayleigh and Gaban; we did not see or hear Roger fighting.
It was never said.
By the way, how will Zoro and Sanji kill someone that Luffy and Roger couldn't? You're not really thinking about it, are you?
Am I, aren't?
They were never supposed to kill them lol. The implications were that Imu would have taken them back or maybe seastone chains would have been used on them when they were "defeated" and in the process of regenerating.
There is also the possibility that since they were "evoked", when defeated they could have simply gone back.
People who thought Zoro and Sanji with freshly awakened CoC could kill HK when Roger, but let's even say prime Gaban and Ray could not, has always been delusional.