ΔE 11.7, fair: the same colour family, but not a straight swap. Morrow White is a little lighter, more muted than Mummy Robes.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Morrow White is a little lighter, more muted than Mummy Robes.
The same difference applies the other way round: Mummy Robes is a little darker, 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 Mummy Robes on the colour wheel See Morrow White on the colour wheel
All matches: Mummy Robes equivalents · Morrow White equivalents