I’m not close to my copy of the graphs, but the logical explanation is that in the PC1 case you are limited buy the first segment climb requirements (100 ft/min at Vtoss, L/G down and 2 min OEI power from 35-200 ft), so you will actually achieve greater than 150 ft/min in the second segment (Vy, L/G up, OEI CT from 200-1000 ft).
In the second example, you may achieve the PC2 requirement but would not achieve the first segment PC1 requirements.
If you check the graphs it should confirm this.