Double chin: Would I need 2 vials of Kybella based on these photos? (photos)

You'll need an in-person evaluation to determine how much Kybella will be needed. Both Kybella or neck liposuction are good options and will improve the double chin. It depends on your lifestyle and personality which would be better for you. 
Kybella is best for patients that:
1)  Do not want surgery 
2)  Are not surgical candidates 
3)  Not willing to wear a compression dressing around the face for 1 week 
4)  Patient-  The results of Kybella will take months
Kybella take 1-3 treatments every 6 weeks.  Patient will develop swelling and possible bruising after each injection that may last a few days.  The benefit of Kybella is each treatment is quick and completed in the office. However, some patients need more than one treatment to get desired results. 
Neck Liposuction is best for patients that:
1)  Want a single treatment 
2)  One recovery time-  Downtime for neck liposuction require wearing a wrap around face for 1 week. 3)  Less painful 
4)  Quicker results 
5)  Cost is a concern
Neck liposuction is a quick surgical procedure that can be complete while the patient is awake.  It cost around the same price a Kybella and can be less in patients with heavier necks.  The single recovery of neck liposuction may be a better option for some patients.
I hope this helps.

Newer algorithms for Kybella are 2 vials spaced 2 months apart and in your case I suspect you'll need between 6 and 8 vials total.