Wiki can you code 64635 and 64636 with (64493 and 64494)

It is either a MBB/Facet injection or a Radiofrequency. I doubt the physician would do both at the same visit.

Melissa Harris, CPC
The Albany and Saratoga Centers for Pain Management
Radiofrequency Bilateral Billing

How do you bill 64635 and 64636 if it is done bilaterally? Is it with a 50 modifier or Rt and Lt? My CPT books says to use 50 but do most insurances follow this? Please advise.