Both twins think they are identical, but have not confirmed it through any DNA testing.
Stephen and Carroll Ratpojanakul are parents to 16-month-old Reed.
When Reed came over to his uncle and aunt's house, Stephen and Michael Ratpojanakul figured they'd test him to see if he knew who his dad was, and got it on video.
First, Reed is in his dad's arms, and points to his uncle, Michael Ratpojanakul.
"Dada," Reed says, and reaches for him.
When he is handed to his uncle and looks back at his dad, he says, "Dada," and reaches for Stephen Ratpojanakul.
The brothers erupt in laughter.
The Facebook post, uploaded Frday, has over 9 million views.
Family members say they've tried the same trick in the past with Reed's mom and aunt, but it didn't work.
"No matter how identical they are, a baby always knows his mama,” Stephen Ratpojanakul said.
Watch the video below.