User blog comment:JERealize/Progress Bar: Issue 053 (TDPI Episode 3 Review)/@comment-1874924-20140802183228

The fact that nobody except Jasmine seemed able to tell the twins apart by Amy's mole (well, maybe Chris could, but being Chris, he doesn't care) suggests to me that Amy's mole is a meta construct. In other words, Amy doesn't actually have a mole in-universe, and it's only there so that we, the viewers from beyond the Fourth Wall, can tell the twins apart.

Technical note: "Smitten" is what's happening to Rodney in every episode. It's pretty much lost its connection to "smite".