The effect of VPL method

Hi ,
I had trained a FR model with arcFace_torch method in 8 GPUs, and the accuracy of it is LFW 99.85, CFP_FP 99.12, AGEDB_30 98.48；Simultaneously, I had train another model with VPL_arcface ( 'vpl': {'start_iters': 20000, 'allowed_delta': 80, 'lambda': 0.15, 'mode': 0, 'momentum': True}) in 4 GPUs, and the accuracy of it is LFW 99.85, CFP_FP 99.14, AGEDB_30 98.43. The VPL method don't seem to be working,I don't know the reason.