Sama-Vishama bala

Hi Ernst,

I have read elsewhere that if Chandra/Shukra are in an even sign in rashi AND navamsha, they get a strength of a total of 15 virupas. Or 0 otherwise. So their sama-vishama bala is 15 or 0.

However, you state in the Shadbala audio class that Chandra/Shukra get 15 virupas if in an even sign in rashi, and another 16 virupas if in an even sign in navamsha, for a total of 30 virupas. So their sama-vishama bala is 0, 15 or 30.

I have a couple of questions as a result:

1. Are there two methods to calculate Sama-Vishama Bala? Parashara is silent on this in the BPHS. 

2. Is there an option in Kala to use one method or the other?

Thanks in advance.

Anil