ΔE 15.8, loose: different enough that you should pick on purpose. Old Gold is noticeably darker, warmer than Necro Gold.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Old Gold is noticeably darker, warmer than Necro Gold.
The same difference applies the other way round: Necro Gold 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 Necro Gold on the colour wheel See Old Gold on the colour wheel
All matches: Necro Gold equivalents · Old Gold equivalents