That is not accurate.
In phase 1 dh generates 3 sub keys SKe, SKa SKd. SKd will be generated 1st
to obtain SKe and SKd. If PFS is off, then you use same keys for phase two
encryption/hashing and you don't generate new sub keys. If you have PFS on
then new set of sub keys generated.
Different encryption/decryption keys is the case when using certificate
authentication.