Subject: How common are 2 albinos in a clutch of 3 blue and gold macaws?

I hatched 3 chicks in one clutch from a pair of normal blue and gold 
macaws that I have raised about 20 normal chicks before.  This time there 
are 2 albinos (or leucistic) and 1 normal.  They have red eyes, white 
beaks,toes, and skin. Around their face are gold feathers and their body 
is a creamy light yellow. There is no other color - like the blue, green, 
or black.  Is this common in macaws?  Are they twins (they are both 
males)? Will this happen again from these parent birds?

Re: How common are 2 albinos in a clutch of 3 blue and gold macaws?