neko:
There are tens possible reasons for having the same dream, or thinking you've had the same dream, that do not involve the siddhis or anything supernatural at all. From having seen the same scene on the TV, to false memories, to confirmation bias (focusing on the similarities of the dreams instead of the differences) to archetypes (most people's dreams are very similar anyway). And on, and on, and on.
Man, I'm not in the position to prove anything and my first thoughts were "It must have any Freudian explanation I don't know". But the fact is that it wasn't something like "we both dreamt with snakes". We had literaly the same dream with all its details (we were both there, me and my friend, in "both" dreams, in the same place - a hut he owns in the countryside. We were able to identify the same people (and unable to identify the same amount of people), and describe the same little incidents (the presence of two blond yet tanned male twins -not identifiable-, one of which was raped by a mob in the shower - I never said it wasn't a weird unpleasant dream -, the arrival of my friend's mother in a car, and then we running naked up the hill, which became higher as we climbed it, as the perspective of "the dreamer" changed from first-person to a third person who stood flying above. I'm mean, there's too many specific details not to be impressed with, and not a single difference. Plus the fact that I let my friend report part of the dream (I didn't just told him as he agreed, I wanted to be sure he wasn't kidding), and the fact that I had earlier that night dreamt about what he was doing (trying to fix his notebook) in the other room.
But that's not the point anyway, my question was directed towards people who have experienced something similar through the practice of this particular (non-Buddhist) meditation, and found out if there's any utility in developing it.
(sorry, english is not my first language)
(But I agree with that one must always doubt its recollections and be aware of cognitive biases)