ΔE 15.4, loose: different enough that you should pick on purpose. Viper Brown is noticeably lighter, more saturated, warmer than Human Flesh.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Viper Brown is noticeably lighter, more saturated, warmer than Human Flesh.
The same difference applies the other way round: Human Flesh is noticeably darker, more muted, cooler.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Human Flesh on the colour wheel See Viper Brown on the colour wheel
All matches: Human Flesh equivalents · Viper Brown equivalents