It started by trying to look up the Tichborne case, which if you've never read about it you might have heard of offhand. There's a missing heir, a guy that randomly shows up and claims to be the man (much changed by the years of course), and then many years and lawyers pass while everyone tries to figure out if he's really the baronet. Lady Tichborne thought he was, other family members didn't. And, drama. You can see why everyone gossiped about this for 20+ years and many contemporary authors worked it into various plots or conversations in their books, plays, you name it. And oh spoiler, the man wasn't really the heir. That wikipedia link above gives you a good rundown and images, plus references.
So what I bumped into while googling for the case using the word "heir" (I never remember the name Tichborne), was Edward Mordake. (Which is an excellent "use this in a novel" kind of name.) Let me post the first sentence of the wikipedia page to show you why that gave me a "wait, what" moment:
Edward Mordake (sometimes spelled Edward Mordrake) was reportedly an heir to an English peerage who had an extra face on the back of his head. The duplicate face could neither eat nor speak out loud but was seen to "smile and sneer while Mordake was weeping." Mordake reportedly begged doctors to have his "Demon face" removed, claiming that it whispered to him at night, but no doctor would attempt it. He committed suicide when he was 23 years old.
There's a melodramatic quote of his story from 1896's Anomalies and Curiosities of Medicine - and a link to the text in Google books.
Happily there's always a good site to check for stuff like this (wikipedia includes a link to it): The Museum of Hoaxes: Edward Mordake. Apparently this story gets circulated online a lot (no surprise there, huh) and there's a sample image that's shown - which isn't a photo at all:
However, this isn't a photograph of the actual Mordake. Instead, it's a photo of a wax replica created by an artist to show what Mordake might have looked like. Where this wax figure was displayed, or by whom it was created, I'm not sure, but various replicas of Mordake have been created over the years for wax museums around the world.
[Off tangent! Refraining from a rant here about circulating Real History! or Amazing and True! sorts of stories, tumblrites. I'm on tumblr too, btw. But almost all the biographies I've seen in the mini-summary-plus-photo are badly done if not badly fact checked. Believe them only when they care enough to cite a source. Because pointing someone to a full biography website or a book means you care about history more than how many likes and shares you'll get with a graphic.]
Read the rest of that page for more on how the website author Alex Boese proposes that Edward Mordake and his story were a fictional creation. And he backs up his theory with what the site does well - research and citation:
I did a keyword search of the archive of 19th-century American papers at newspapers.com (which requires a subscription) and discovered that Mordake's story appeared in an article written by the poet Charles Lotin Hildreth that ran in American papers in 1895, approximately a year before the publication of Gould and Pyle's book.
And if you want a more lighthearted story after that - check out his blog post on Cheeseburger Oreos. Which thankfully do not exist. Blearg.
[I became a fan of the Museum of Hoaxes for its coverage of The Great Moon Hoax. It even has the original text of the New York Sun's articles in an easy to read format -compared to trying to read the original tiny print in the papers of 1835.]