ΔE 17.3, loose: different enough that you should pick on purpose. Saddle Brown is noticeably lighter, more muted than Perylene Violet.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Saddle Brown is noticeably lighter, more muted than Perylene Violet.
The same difference applies the other way round: Perylene Violet is noticeably 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 Perylene Violet on the colour wheel See Saddle Brown on the colour wheel
All matches: Perylene Violet equivalents · Saddle Brown equivalents