A rate like this:

Will jump to tier 2 at 50 kWh:
-https://github.com/NREL/ssc/blob/6825d95b3263d0f1f3aa23a9661f646cd874ac0d/ssc/cmod_utilityrate5.cpp#L2452
-https://github.com/NREL/ssc/blob/6825d95b3263d0f1f3aa23a9661f646cd874ac0d/ssc/cmod_utilityrate5.cpp#L2498
which will ignore the 100 kWh entry in period 2. I think this is the correct behavior based on PG&E documents like https://www.pge.com/assets/pge/docs/account/rate-plans/residential-electric-rate-plan-pricing.pdf (see “TOU in the 2nd set of charts).
That said, different tiers in different periods could be valid if the periods are spread across different months
A rate like this:

Will jump to tier 2 at 50 kWh:
-https://github.com/NREL/ssc/blob/6825d95b3263d0f1f3aa23a9661f646cd874ac0d/ssc/cmod_utilityrate5.cpp#L2452
-https://github.com/NREL/ssc/blob/6825d95b3263d0f1f3aa23a9661f646cd874ac0d/ssc/cmod_utilityrate5.cpp#L2498
which will ignore the 100 kWh entry in period 2. I think this is the correct behavior based on PG&E documents like https://www.pge.com/assets/pge/docs/account/rate-plans/residential-electric-rate-plan-pricing.pdf (see “TOU in the 2nd set of charts).
That said, different tiers in different periods could be valid if the periods are spread across different months