As you may see from my hub (Every word has a story: Devils, Damask and Doppelgänger) superstition is that if you ever see one, it means it is a harbinger of death!
I personally have not see mine but I did pretend to have one about town when I was caught going to the pictures when I should have been at College. I said there must been 'another' who looks just like me. This imaginary doppelgänger helped me out of many sticky situations. I am just glad my Dad doesn't read hubpages.
Or does he... oops!
And ptosis, do you by any chance have siblings called miosis and anhidrosis? ;-)