ΔE 11.3, fair: the same colour family, but not a straight swap. Olive Drab is a little darker, more saturated, cooler than Dark Mustard Khaki.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Olive Drab is a little darker, more saturated, cooler than Dark Mustard Khaki.
The same difference applies the other way round: Dark Mustard Khaki is a little lighter, more muted, warmer.
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 Dark Mustard Khaki on the colour wheel See Olive Drab on the colour wheel
All matches: Dark Mustard Khaki equivalents · Olive Drab equivalents