Most of my chickens have different colours. I do have two black Dutch though,  I couldnāt keep apart.  I called them Black Pearl 
. A double name for both of them. I didnāt mind not being able to see the difference until one got broody and I tried to break her broodiness. I wanted to kick her out the nest but wasnāt sure if she already stopped being broody . And I didnāt want to disturb a laying hen (her twin sister). 
At an impulse I took some paint I was working with (non toxic outdoor paint) and smeared a little white paint on a few feathers. It stayed there until she molted. After the molt one black got brown neck feathers and the other didnāt .
 Now these chickens have a personal name: totally Black and rusty Pearl. 
Since last spring I have another twin pair. 2 bantam RIR. They look the same , but behave differently. Kwekky is always one of the first to free range if I open the door. And Katrientje is super shy and doesnāt trust me. She doesnāt come out of the coop until after I leave the door opening.
As long as I donāt have issues I donāt mind the look-a-likes. Next time I might buy rings. Advantage to wait until they have grown to adults is that there are no problems with tight rings. And bc I donāt breed with them there is no need to ring/ distinguish the chicks.
	
		
			
		
		
	
				
			At an impulse I took some paint I was working with (non toxic outdoor paint) and smeared a little white paint on a few feathers. It stayed there until she molted. After the molt one black got brown neck feathers and the other didnāt .
Since last spring I have another twin pair. 2 bantam RIR. They look the same , but behave differently. Kwekky is always one of the first to free range if I open the door. And Katrientje is super shy and doesnāt trust me. She doesnāt come out of the coop until after I leave the door opening.
As long as I donāt have issues I donāt mind the look-a-likes. Next time I might buy rings. Advantage to wait until they have grown to adults is that there are no problems with tight rings. And bc I donāt breed with them there is no need to ring/ distinguish the chicks.
	