ΔE 13.4, fair: the same colour family, but not a straight swap. Ivory RLM05 is noticeably lighter, more muted than Dune Shadow.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Ivory RLM05 is noticeably lighter, more muted than Dune Shadow.
The same difference applies the other way round: Dune Shadow 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 Dune Shadow on the colour wheel See Ivory RLM05 on the colour wheel
All matches: Dune Shadow equivalents · Ivory RLM05 equivalents