Rhode island red laying white eggs ??

Are you sure that it's a Rhode Island Red? And are you sure that you don't have a different bird that could be laying the white eggs?

 

By "Americana", do you mean Ameraucana or Easter Egger?
And your profile pic does not show two Rhode Island Reds. The hens in that photo are red sexlinks.

 

I was curious so I did a quick Google search, turns out there are a few reasons that this can happen. Calcium not being absorbed properly, a stressed bird, a sick bird, ect. The article I read stresses that you should not jump to conclusions about what's causing it (so many people try to diagnose their birds with some off the wall disease). I'd wait to see if it continues and in the meantime maybe throw some oyster shell in the coop.

 

It could also be that one of the birds is a white egg layer and has been misidentified by the owner....

 

Sure.......but interestingly enough it is a real thing

 

How long has this been going on?

I have had brown eggers that laid very light/white-ish eggs from time to time. Not consistently, just like they forgot to apply the brown coating before the egg was passed. It's no biggie.

If it's an ongoing thing, my next question would be, is the egg white-white, like a grocery store egg, or creamy beige? If ti's not stark white, it's within the normal variation of brown egg layers.