ΔE 13.0, fair: the same colour family, but not a straight swap. Skeleton Brown is noticeably darker, warmer than Mummified Grime.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Skeleton Brown is noticeably darker, warmer than Mummified Grime.
The same difference applies the other way round: Mummified Grime is noticeably lighter, 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 Mummified Grime on the colour wheel See Skeleton Brown on the colour wheel
All matches: Mummified Grime equivalents · Skeleton Brown equivalents