<p>I went to <a href="https://iancoleman.github.io/bip39/" rel="noreferrer">https://iancoleman.github.io/bip39/</a>
and after generating a dozen or so mnemonics I got </p>

<blockquote>
  <p>audit again guess <strong>butter</strong> minute predict grid image fresh kit west will before noodle supply magic bread protect mimic <strong>butter</strong> credit tragic recipe clarify</p>
</blockquote>

<p>So this confirms the other answers: assuming this is a correct implementation, repeats are allowed.</p>

CC BY-SA 3.0
2017-09-24T02:38:06.067Z
2017-09-24T02:38:06.067Z
Nate Eldredge
<p>No, the BIP39 construction does not avoid repeating words.</p>

<p>It is possible for a word to show up multiple times, but since there are 2048 words it is fairly unlikely for repeats to show up in randomly generated keys.</p>

CC BY-SA 4.0
2023-03-21T12:14:02.083Z
How is this wrong? 12.7% of the time is not likely.
G. Maxwell
CC BY-SA 3.0
2017-09-24T02:16:59.997Z
2017-09-24T02:16:59.997Z
G. Maxwell
<p>In fact,</p>
<p>A mnemonic derived of Raw binary @256 bits using all 1's would be as follows.</p>
<p>zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo vote</p>
<p>1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111</p>

CC BY-SA 4.0
2021-01-03T22:24:42.783Z
2021-01-03T22:24:42.783Z
CryptoFlippo
<p>There is nothing stopping a word to be repeated more than once. In a 24 word mnemonic, with 2048 possible words in the dictionary (BIP 39), there is a probability of at least one duplicate around 12.7% of the time (variation of the birthday paradox).</p>

CC BY-SA 3.0
2017-10-23T14:34:50.623Z
Preventing duplicate words will in fact restrict the entropy of the seed phrase.
pim
CC BY-SA 3.0
2017-09-24T02:22:25.620Z
2017-09-24T02:22:25.620Z
meshcollider
<p>Will all 24 words of a seed-phrase be unique by specification? Or is it possible for a word to occupy two positions (ie the word "tool" is #8 AND #20 in a valid, securely generated seed)</p>

<seed><mnemonic-seed>
Does BIP39 mnemonic construction avoid repeating words?
pinhead
# Does BIP39 mnemonic construction avoid repeating words?

(Asked by: username_0 on 2017-09-24)

Will all 24 words of a seed-phrase be unique by specification? Or is it possible for a word to occupy two positions (ie the word "tool" is #8 AND #20 in a valid, securely generated seed)

**Tags:** seed, mnemonic-seed


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## 4 answers

### Answer by username_4 on 2017-09-24. Score: 16 | Accepted answer

There is nothing stopping a word to be repeated more than once. In a 24 word mnemonic, with 2048 possible words in the dictionary (BIP 39), there is a probability of at least one duplicate around 12.7% of the time (variation of the birthday paradox).

> **Comments:**
> **username_5**: Preventing duplicate words will in fact restrict the entropy of the seed phrase.  

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### Answer by username_1 on 2017-09-24. Score: 8

I went to <https://iancoleman.github.io/bip39/>
and after generating a dozen or so mnemonics I got

> audit again guess **butter** minute predict grid image fresh kit west will before noodle supply magic bread protect mimic **butter** credit tragic recipe clarify

So this confirms the other answers: assuming this is a correct implementation, repeats are allowed.


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### Answer by username_2 on 2017-09-24. Score: 5

No, the BIP39 construction does not avoid repeating words.

It is possible for a word to show up multiple times, but since there are 2048 words it is fairly unlikely for repeats to show up in randomly generated keys.

> **Comments:**
> **username_2**: How is this wrong? 12.7% of the time is not likely.  

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### Answer by username_3 on 2021-01-03. Score: 1

In fact,

A mnemonic derived of Raw binary @256 bits using all 1's would be as follows.

zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo vote

1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111


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