“I failed my Calculus exam because I was seated between two identical twins…” (joke)

A calculus joke was posted on Reddit—Dadjokes on July 25, 2018:
   
“I failed my calculus exam in college because I was seated between two identical twins. I couldn’t differentiate between them.”
 
The joke was posted by the same poster on Reddit—Jokes on October 18, 2019, and again on Reddit—Dadjokes on March 21, 2020.
   
   
Reddit—Dadjokes
Posted by u/porichoygupto July 25, 2018
I failed my calculus exam in college because I was seated between two identical twins.
I couldn’t differentiate between them.
   
Twitter
Dad Jokes by dadbot
@dadbot2000
I failed my calculus exam in college because I was seated between two identical twins. I couldn’t differentiate between them. https://ift.tt/2v6n8SY
9:29 AM · Jul 25, 2018·IFTTT
 
Reddit—Jokes
Posted by u/porichoygupto October 18, 2019
I failed my calculus exam because I was seated between two identical twins.
I couldn’t differentiate between them.
   
Twitter
Brata George
@BrataGeorge
I failed my calculus exam because I was seated between two identical twins. I couldn’t differentiate between them. #smile #reddit #jokes
1:04 PM · Oct 18, 2019·IFTTT
 
Reddit—Dadjokes
Posted by u/porichoygupto March 21, 2020
I failed my Calculus exam because I was seated between two identical twins.
It was hard to differentiate between them.
 
Twitter
J
@Testycoal
I failed my Calculus exam because I was seated between two identical twins.
It was hard to differentiate between them.
3:04 PM · Mar 21, 2020·Twitter for Android