ΔE 19.6, loose: different enough that you should pick on purpose. Ivory RLM05 is a little darker, more saturated, warmer than Duck Egg Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Ivory RLM05 is a little darker, more saturated, warmer than Duck Egg Green.
The same difference applies the other way round: Duck Egg Green is a little lighter, more muted, 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 Duck Egg Green on the colour wheel See Ivory RLM05 on the colour wheel
All matches: Duck Egg Green equivalents · Ivory RLM05 equivalents