ΔE 56.9, loose: different enough that you should pick on purpose. Mahogany Ink is noticeably darker, warmer than Matt Sky Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 57). Mahogany Ink is noticeably darker, warmer than Matt Sky Blue.
The same difference applies the other way round: Matt Sky Blue is noticeably lighter, 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 Matt Sky Blue on the colour wheel See Mahogany Ink on the colour wheel
All matches: Matt Sky Blue equivalents · Mahogany Ink equivalents