Compare the result of the first rollout with the result of the second rollout (at the bottom of this post, also posted elsewhere in this thread). The only difference is that White has played an extra 13/8 in the first position.
Here is a nacbrac summary (both XG2 3-ply 5k rollouts) to spotlight the .058 difference in margin:
63S-62X-F-51P-32 [@ P33]
63S-21X-F-51P-32 [P @25]
Nack

              
 
              
 | | White is Player 2
score: 0 pip: 153 | Unlimited Game Jacoby Beaver | pip: 165 score: 0
Blue is Player 1 | |
| XGID=-a-a--E-C-A-cD---cbe----AA:0:0:1:32:0:0:3:0:10 |
| Blue to play 32 |
| 1. | Rollout1 | Bar/22 24/22 | eq: -0.278 |
| Player: Opponent: | 42.84% (G:10.01% B:0.34%) 57.16% (G:12.96% B:0.51%) | Conf.: ± 0.007 (-0.285...-0.270) - [100.0%] Duration: 4 hours 32 minutes |
|
| 2. | Rollout1 | Bar/23 13/10 | eq: -0.310 (-0.033) |
| Player: Opponent: | 43.04% (G:10.93% B:0.43%) 56.96% (G:17.89% B:0.71%) | Conf.: ± 0.008 (-0.318...-0.302) - [0.0%] Duration: 3 hours 56 minutes |
|
| |
1 5184 Games rolled with Variance Reduction. Dice Seed: 82300325 Moves: 3-ply, cube decisions: XG Roller
|
eXtreme Gammon Version: 2.01

              
 
              
 | | White is Player 2
score: 0 pip: 158 | Unlimited Game Jacoby Beaver | pip: 165 score: 0
Blue is Player 1 | |
| XGID=-a-a--E-C-A-dD---bbe----AA:0:0:1:32:0:0:3:0:10 |
| Blue to play 32 |
| 1. | Rollout1 | Bar/23 13/10 | eq: -0.188 |
| Player: Opponent: | 45.63% (G:11.60% B:0.45%) 54.37% (G:15.30% B:0.62%) | Conf.: ± 0.007 (-0.195...-0.180) - [100.0%] Duration: 1 hour 04 minutes |
|
| 2. | Rollout1 | Bar/22 24/22 | eq: -0.213 (-0.025) |
| Player: Opponent: | 44.41% (G:10.56% B:0.40%) 55.59% (G:12.56% B:0.52%) | Conf.: ± 0.008 (-0.220...-0.205) - [0.0%] Duration: 1 hour 12 minutes |
|
| |
1 5184 Games rolled with Variance Reduction. Dice Seed: 36474524 Moves: 3-ply, cube decisions: XG Roller
|
eXtreme Gammon Version: 2.01