After making a somewhat speedy recovery from that shooting incident in the Season 7A finale, Spencer appears to be on the mend and she's enjoying some quality time with Detective Marco Furey. I just can't quit the theory that Spencer has a twin on Pretty Little Liars — the clues began to pile up rapidly last season, and a quick walk down memory lane showed that hints have been present for longer than we may have thought. In the May 2 episode, there was a super subtle clue that lends further credence to the twin theory. In fact, it was so subtle that I totally missed it until it was brought to my attention by the hosts of Bustle's Pretty Little Liars podcast Taking This One to the Grave.
During the episode, Spencer and Marco played a game of table tennis and it became a bit competitive. Reddit user CaitlinDiLaurentis made an astute observation that most of us probably missed — in order to score the winning point, Spencer switched the paddle from her right hand to her left. We know that Spencer is right-handed, so is it possible that the woman playing table tennis wasn't Spencer at all? At the very least, it would give viewers an explanation for why such a random scene was included in the first place.
Now that it's been confirmed Mary Drake is Spencer's birth mother, it seems more likely than ever that she's a twin. Twins run in the DiLaurentis family and, if you listen closely to Veronica's description of Spencer's adoption, she didn't actually witness the birth itself. Rather, she was in the hospital when Mary gave birth and Spencer was put in her arms very shortly thereafter. So, it's entirely possible that Mary Drake has another child out there that Veronica and Peter aren't aware of.
Another easy to miss clue was recently brought to my attention by Tumblr user the-outlast. When Spencer and Aria visited Dr. Cochran, he said he delivered "two of Mary's babies" rather than "two babies" which implies that she has a third child whose identity is unknown.
The plot device of Spencer having a twin would also be consistent with the show's strategy of borrowing elements from the books, then switching things up. In the book series, SPOILER ALERT Ali has a twin — so it wouldn't be surprising if the twin storyline is used with a different character.
The creepiest part of the Reddit theory? The "Spencer" who has been on screen ever since the time jump is actually her twin. This seems like a definite possibility and if it's true, it begs the question, "Where is Spencer herself?" This is shaping up to be one heck of a final season.