Different result with som.py/hap.py and just compare[chrom-pos-alt-ref] paire

[LeiHaoa]

Hi, I have validated my detect result use hap.py/som.py and just compare [chorm-pos-alt-ref]，but these two functions showed different results. for example, I have test strelka2 with dataset NA12878, the som.py shows strelka2 result's recall is 93%(indel) and 99%(SNV), but when I use script to just compare[chrom-pos-alt-ref](all same value means the same variant), the results is 82%（indel）and 90% SNV. So, I am curious about what difference come form when I use these two different validate function?? and is this reasonable when i just compare [chrom-pos-alt-ref] pair??

Thanks!