Broody hen hatched 2 chicks, I added 2 more and she's attacking

[Alaskan]

Birds can see color, but if they hatch out say all yellow chicks and then two days later you add a black or red one, they'll know it doesn't belong. If they have like 5 colors that they hatched, it's a bit easier to sneak one in if it's the same color as a baby the mom has

Yes, exactly