ΔE 15.2, loose: different enough that you should pick on purpose. Metallic Brown is much more saturated than Hashut Copper.
Can I use Metallic Brown instead of Hashut Copper?
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Metallic Brown is much more saturated than Hashut Copper.
Can I use Hashut Copper instead of Metallic Brown?
The same difference applies the other way round: Hashut 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.