If you look here https://www.vmware.com/learning/certification/vcp-dcv.html and select 'no VCP certifications' on the left you can see what the requirements are. It states that you can either take the 2V0-21.20 or the 2V0-21.23 exams.
If you had already taken and passed the 2V0-21.20 exam then you would only have the option of taking the newer exam.
Attending a required course and passing either of the exams grants you the same certification - VCP- DCV 2023.
Out of interest, which qualifying course did you take?
