ΔE 19.1, loose: different enough that you should pick on purpose. Dark Mud is noticeably darker, more muted, warmer than Dark Mustard Khaki.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Dark Mud is noticeably darker, more muted, warmer than Dark Mustard Khaki.
The same difference applies the other way round: Dark Mustard Khaki is noticeably lighter, 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 Dark Mustard Khaki on the colour wheel See Dark Mud on the colour wheel
All matches: Dark Mustard Khaki equivalents · Dark Mud equivalents