ΔE 10.7, fair: the same colour family, but not a straight swap. Olive Shadow is a little darker, warmer than Dark DAK Green.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Olive Shadow is a little darker, warmer than Dark DAK Green.
The same difference applies the other way round: Dark DAK Green is a little 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 Dark DAK Green on the colour wheel See Olive Shadow on the colour wheel
All matches: Dark DAK Green equivalents · Olive Shadow equivalents