ΔE 11.6, fair: the same colour family, but not a straight swap. Dark Red is a little lighter, warmer than Shadow Red.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Dark Red is a little lighter, warmer than Shadow Red.
The same difference applies the other way round: Shadow Red is a little darker, 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 Shadow Red on the colour wheel See Dark Red on the colour wheel
All matches: Shadow Red equivalents · Dark Red equivalents