ΔE 12.2, fair: the same colour family, but not a straight swap. Ancient Copper is much more saturated than Copper.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Ancient Copper is much more saturated than Copper.
The same difference applies the other way round: Copper is much more muted.
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 Copper on the colour wheel See Ancient Copper on the colour wheel
All matches: Copper equivalents · Ancient Copper equivalents