ΔE 33.7, loose: different enough that you should pick on purpose. Crimson Magenta is noticeably lighter, much more saturated, cooler than Brazen Copper.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 34). Crimson Magenta is noticeably lighter, much more saturated, cooler than Brazen Copper.
The same difference applies the other way round: Brazen Copper is noticeably darker, much more muted, warmer.
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 Brazen Copper on the colour wheel See Crimson Magenta on the colour wheel
All matches: Brazen Copper equivalents · Crimson Magenta equivalents