As you've trained on vSphere 6.0, you are ONLY eligible for VCP6-DCV but NOT VCP6.5-DCV (unless you took another class on 6.5 or 6.7)
So, looking at the VCP6-DCV requirements:
- Attend a 6.0 class = DONE
- Pass either 6.0 Foundations OR 6.5 Foundations exams = DONE
- Pass the VCP6-DCV exam
If you pass the VCP6-DCV exam (code 2V0-621) you would have met the requirements for VCP6-DCV - the fact you passed the Foundations exam on 6.5 is OK.
Note that this exam retires on August 30th (as do all exams based on vSphere 6.0 or 6.5)
From August 31st, only VCP-DCV 2019 will remain - with exams based on vSphere 6.7, and a training requirement for 6.7 too.
That makes perfect sense.