ΔE 15.4, loose: different enough that you should pick on purpose. Undead Flesh is noticeably lighter, more muted, cooler than Mid Mustard Khaki.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Undead Flesh is noticeably lighter, more muted, cooler than Mid Mustard Khaki.
The same difference applies the other way round: Mid Mustard Khaki is noticeably darker, more saturated, 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 Mid Mustard Khaki on the colour wheel See Undead Flesh on the colour wheel
All matches: Mid Mustard Khaki equivalents · Undead Flesh equivalents