Essentially, being eligible to undertake the HSC (year 12) course of a subject depends on whether the subject's Preliminary (year 11) course has been completed. Based on this, taking Studies of Religion II in year 12 requires the completion of the Studies of Religion II Preliminary course. If you have taken SOR I in year 11 and have completed that subject's Preliminary course instead of that of SOR II, you will progress to the SOR I HSC course, that is, it is not possible to move up to SOR II in year 12.
This works differently to subjects such as Mathematics Extension 2 and English Extension 2, both of which are designed to be taken by students in year 12 (i.e. they have no year 11 course) in addition to Mathematics Extension 1 and English Extension 1. In such a case, Mathematics Extension 1 and English Extension 1 are treated as corequisites, meaning that their respective year 12 courses must be completed concurrently (or prior to, in the case of acceleration) with Mathematics Extension 2 and English Extension 2.
Other examples of such subjects include Science Extension, which is a subject to be taken in year 12 only. This subject is also subject to corequisites, as it requires students to be taking at least one of Biology, Chemistry, Earth and Environmental Science, Investigating Science or Physics alongside it in Year 12.
I hope this helps!