ΔE 20.4, loose: different enough that you should pick on purpose. Kiwi Brown is a little lighter, much more saturated, warmer than Dark Mustard Khaki.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Kiwi Brown is a little lighter, much more saturated, warmer than Dark Mustard Khaki.
The same difference applies the other way round: Dark Mustard Khaki is a little darker, much 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 Dark Mustard Khaki on the colour wheel See Kiwi Brown on the colour wheel
All matches: Dark Mustard Khaki equivalents · Kiwi Brown equivalents