Still more confusing...
You have Equipment A & 10 Equipment B.
I hope, this is not parallel process where one Equipment B fails, you can run with another Equipment B.
So, whether Equipment A fails or Equipment B fails, downtime is for 10 min. Then, on what basis, Equipment A may have 100 % production loss whereas Equipment B will have only 10 %.
All are individual equipments & only because of you having Equipment B as 10 numbers, efficiency loss is 100 % / 10 numbers.
MTTR / MTBR are based on individual equipment or functional location. Not based on types or group of equipments.
If you have any logic to design this report, go for custom report. But still, this logic is not convince-able.