I've been googling it and there are examples on COCAE where "have been been" is used that would be too many for a typo.
Oh, OK. So, you're saying it's correct then? Or do you have a third explanation?
In my experience, perseverating like this in writing is quite common. Rather than assuming it's too common to be an error, why not postulate that it's a common error, such as writing two
haves or
hads in a row? Actually it's not strictly a typographical mistake; it's a psychological phenomenon.
In any case, the structure "have been pp" is possible, "I have been seen/killed/..." But it's transitive. Someone can see me, or kill me, but they can't 'be' me.
"I have been gone for three days" is possible. This is intransitive.
Still, if "have been been" can't be an error, I'd be interested to hear your explanation.