is it essential to grow more than one variety of vaccinium corymbosum for cross pollination

you dont have to for this species. so dont worry insects will do it for you.
welcome to GoY, sorry for the delay in replying.

I used to think this too but cross pollination is not necessary. Wind and insects allow a blueberry to get nearly 100% fruit set. Only a few need it due to their own pollen incompatibility eg Goldtraube strain 53. Goldtraube 23(highest of all anti-oxidants) or strain 71 are comfortable with their own pollen and the ones sold in stores. Spartan blueberry needs cross pollination. Brigitta blueberry has poor ability to be self fertile due to a problem with flower shape or corona. Only these two I know of need cross pollination and are poor self croppers. Patriot is highly self fertile as are Bluecrop and Reka!