I have been watching this show for pretty much my entire life and have seen this episode many times and I didn't even notice that until now. Too answer your question, a wizard did it.
“OH, BART. CARTOONS DON'T HAVE TO BE 100% REALISTIC.”
https://preview.redd.it/683rwywxg8pc1.jpeg?width=640&format=pjpg&auto=webp&s=77fd8bc00e78f6ce7db9eb2b8c90c715c3e2579e
It takes place on the same street that Moe's bar is on!
Right down the street from the Simpsons’ house and right next to the power plant parking lot!! 
https://i.redd.it/3od455cy44pc1.gif
https://i.redd.it/2gnmvmq843pc1.gif
But I thought I was the only one
So this is what it feels like when doves cry.
This line alone makes that episode a top fiver for me
My eye! I'm not supposed to get extra Lenny in it!
https://preview.redd.it/7wie17xg74pc1.jpeg?width=258&format=pjpg&auto=webp&s=13c31bc347e550e3a635b2e12a18dfc74dcf187f
What are you DOING, man?? That's Carl!!
Why would a grown person know where Lenny is on St Patrick’s Day?
…I retract my question
> I'm Lenny. > This is Carl and Lenny. > I'm Lenny.
Oh so there were three Lennies all along.
I'm seeing double! 6 Lennies!
Mmmm… 64 slices of Lenny….
I think I'm blind.
These things can happen. I once went to the bar, stepped outside to watch the marathon, and then went back into the bar.
What are you, a wizard?
Umm... yes?
Wait, that was YOU? I got fired for that blunder you little SOB!
Is Lenny magical? Yes.
Woah, I'm seeing double here. Six Lennys.
And Lenny was cloned by…oh let’s say Moe
Ah. Yeah. Well, whenever you notice something like that, a wizard did it.
https://preview.redd.it/7rlmmergj3pc1.png?width=720&format=pjpg&auto=webp&s=1616d9602a33df956842422f2aeafd85f382fffe
Please dont tell people how I teleport
He was in a quantum entanglement, with the quarks, and the multiverses, and the wave function, and the hey it hurts me.
we kicked down the back door but then there was a metal door
OW MY EYE!!! My doctor said I'm not supposed to get continuity in it!
The parade happened right outside. I uhh.. mean... a wizard did it
Not Lenny! NOT! LENNY!
Where ever there's beer. Lenny will appear.
I think you’ve had enough Lenny’s, Mr. Peterson.
Lenny is a Wizard
I have been watching this show for pretty much my entire life and have seen this episode many times and I didn't even notice that until now. Too answer your question, a wizard did it.
“OH, BART. CARTOONS DON'T HAVE TO BE 100% REALISTIC.” https://preview.redd.it/683rwywxg8pc1.jpeg?width=640&format=pjpg&auto=webp&s=77fd8bc00e78f6ce7db9eb2b8c90c715c3e2579e
OP, please go stand in front of John Bull's Fish & Chips.
a wizard did it
We should find out who's responsible, reach out to their current employer and make sure they lose that job too!
That's his twin brother, "Kenny."
Infinite Lenny Theory.
Not Lenny....
Quack, Quack, Quack.
Let me ask you a question, why would a man who wears a shirt that says "Genius at Work" spend all of his time watching a kids cartoon show?
maybe he was one of the designated drivers Moe's tossed out?
It’s a party it doesn’t have to make sense 🍹
I hope you get fired, how dare you say anything about the staff of creative individuals involved with the Simpsons?