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Why Do Clones Keep Multiplying Infinitely?

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CM

CodeExplorer_Maya

Posted on July 22, 2025 • Intermediate

🤔 Clone Multiplication Mystery

I’m running into a weird issue with clones that’s driving me crazy! I have this simple setup where I want to create just ONE clone when the stage is clicked, but instead it keeps multiplying like crazy. Here’s my code:

Stage:

    when stage clicked
broadcast [create clone v]

Sprite:

    when I receive [create clone v]
create clone of [myself v]

when I start as a clone
go to [random position v]

Instead of creating just one clone, it creates 2, then 4, then 8, then 16… It just keeps doubling! 😵 I thought it would only create one clone each time I click the stage, but something weird is happening.

Why does it multiply instead of just adding one clone? I’m so confused! 🤷‍♀️

CS

CloneSpecialist_Dev

Replied 20 minutes later • ⭐ Best Answer

@CodeExplorer_Maya Ah, you’ve discovered one of Scratch’s most common “gotchas”! 😄 This is actually expected behavior, but it catches everyone off guard at first.

🔍 What’s Actually Happening

Here’s the key insight: Clones also respond to broadcast messages! Let me show you what’s happening step by step:

flowchart TD A[🖱️ Stage Clicked] --> B[Broadcast 'create clone'] B --> C[Original Sprite receives message] C --> D[Creates Clone #1] B --> E[Clone #1 also receives message!] E --> F[Creates Clone #2] B --> G[Clone #2 also receives message!] G --> H[Creates Clone #3] B --> I[And so on...] style A fill:#e1f5fe style D fill:#e8f5e8 style F fill:#fff3e0 style H fill:#fce4ec style I fill:#ffebee

🛠️ Solution 1: Use Direct Clone Creation

The simplest fix is to have the stage create the clone directly:

    when stage clicked
create clone of [Sprite1 v]

// In the sprite:
when I start as a clone
go to [random position v]

🛠️ Solution 2: Use a Control Variable

If you need to use broadcasts, add a control mechanism:

    // Create a variable called 'can create clone' for all sprites

when green flag clicked
set [can create clone v] to [yes]

when stage clicked
broadcast [create clone v]

when I receive [create clone v]
if <(can create clone) = [yes]> then
set [can create clone v] to [no]
create clone of [myself v]
wait (0.1) seconds
set [can create clone v] to [yes]
end

🛠️ Solution 3: Clone Counter Method

For more precise control, use a counter:

    // Create variable 'clone id' for all sprites

when green flag clicked
set [clone id v] to [0]

when stage clicked
change [clone id v] by [1]
broadcast [create clone v]

when I receive [create clone v]
if <(clone id) = [1]> then
create clone of [myself v]
set [my id v] to (clone id)
end

when I start as a clone
if <(my id) = (clone id)> then
go to [random position v]
end

💡 Why This Happens

This behavior exists because clones are full copies of the original sprite, including all their scripts. When a broadcast is sent, every sprite and clone that has a matching “when I receive” block will execute it simultaneously.

It’s actually quite powerful once you understand it - you can use it to coordinate actions across all clones! But for simple clone creation, it definitely trips people up. 😅

CM

CodeExplorer_Maya

Replied 45 minutes later

@CloneSpecialist_Dev OMG thank you so much! 🤯 I had no idea clones could receive broadcast messages too!

I used the direct clone creation method and it works perfectly now. Just one clone each time I click, exactly what I wanted. This explains so many weird behaviors I’ve seen in my other projects too!

The diagram really helped me visualize what was happening. Scratch is more complex than I thought! 😄

PT

ProgrammingTeacher_Bob

Replied 2 hours later

Great explanation @CloneSpecialist_Dev! 👏 This is definitely one of the top 5 “Scratch surprises” I see students encounter.

Here’s a teaching tip: I always tell my students to think of clones as “identical twins” - they look the same, act the same, and hear the same messages. If you want only one to respond, you need to give them different “instructions” (like the ID system shown above).

Another common place this trips people up is with collision detection between clones! 🎯

VB

Vibelf_Community

Pinned Message • Moderator

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