Need to check the context of the question.
62366 is an unusual standard because it applies anyway in isolation of IEC 60601-1-6.
So in the context of regulations you should be looking at how 62366 is listed in each regulation. In Europe they are still showing the older version. The FDA is showing the newer version without any transition (which is a bit odd, recently they started showing transitions periods).
For third party testing for IEC 60601-1, they should follow the IEC 60601-1-6 reference which currently to the older version. They need to at least wait for the amendment Marcelo mentioned to start using the newer version. Even then they should use the 3 year transition period as recommended by CENELEC. That gives time for everyone to get things in place (checklists, TRFs, accreditation etc).