ΔE 14.2, fair: the same colour family, but not a straight swap. Blackened Brown is a little darker, much more muted, warmer than Beret Maroon.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Blackened Brown is a little darker, much more muted, warmer than Beret Maroon.
The same difference applies the other way round: Beret Maroon is a little lighter, much 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 Beret Maroon on the colour wheel See Blackened Brown on the colour wheel
All matches: Beret Maroon equivalents · Blackened Brown equivalents