ΔE 18.2, loose: different enough that you should pick on purpose. Wrack White is a little lighter, much more muted than Dead Magenta.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Wrack White is a little lighter, much more muted than Dead Magenta.
The same difference applies the other way round: Dead Magenta is a little darker, much more saturated.
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 Dead Magenta on the colour wheel See Wrack White on the colour wheel
All matches: Dead Magenta equivalents · Wrack White equivalents