ΔE 11.2, fair: the same colour family, but not a straight swap. Saddle Brown is more muted, warmer than Undead Skintone.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Saddle Brown is more muted, warmer than Undead Skintone.
The same difference applies the other way round: Undead Skintone is more saturated, 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 Undead Skintone on the colour wheel See Saddle Brown on the colour wheel
All matches: Undead Skintone equivalents · Saddle Brown equivalents