<blockquote>
  <p>Can two blocks have the same Previous hash after being created.</p>
</blockquote>

<p>Yes, two otherwise valid blocks could be created that both link to the same parent block, but importantly: <strong>only one of those two blocks will become a part of the valid chain</strong>. So ultimately, only one of them will be valid, and the winner will be the block that miners build on top of first (and thus it becomes a part of the longer chain). </p>

<p>The other block will become what is called an <a href="https://bitcoin.stackexchange.com/questions/5859/what-are-orphaned-and-stale-blocks">'orphan block'</a> (though some people prefer the more exact term, 'extinct block'). </p>

<p>You can look through the <a href="/questions/tagged/orhpaned-blocks" class="post-tag" title="show questions tagged &#39;orhpaned-blocks&#39;" rel="tag">orhpaned-blocks</a> tag for more info. </p>

CC BY-SA 4.0
2019-02-20T23:11:21.527Z
What happens to the transactions on the orphan block?
Juan
CC BY-SA 4.0
2019-02-20T23:12:14.783Z
@Juan simply: they are no longer a part of the blockchain record.
chytrik
CC BY-SA 4.0
2019-02-20T23:12:53.880Z
So that money is gone for good? The money X person sent to z person no longer exists?
Juan
CC BY-SA 4.0
2019-02-20T23:14:26.607Z
@Juan no, the bitcoin would still exist, but the transaction sending it from X->Z would not (unless that transaction is also confirmed in the longest valid chain).
chytrik
CC BY-SA 4.0
2019-02-20T23:15:16.247Z
Oh okay, so you would have to send the transaction again so Z can get it
Juan
CC BY-SA 4.0
2019-02-20T23:19:46.197Z
@Juan: In fact, other miners will normally consider transactions from the orphan block for inclusion in future blocks on the main chain.  So the sender typically doesn't have to do anything except wait a little longer for confirmation.
Nate Eldredge
CC BY-SA 4.0
2019-02-20T23:10:10.580Z
2019-02-20T23:10:10.580Z
chytrik
<p>Can two blocks have the same <strong>Previous</strong> hash after being created.</p>

<p>2 blocks totally different from each other but with the same previous hash </p>

<blockchain>
Can 2 blocks have the same previous hash?
Juan
# Can 2 blocks have the same previous hash?

(Asked by: username_0 on 2019-02-20)

Can two blocks have the same **Previous** hash after being created.

2 blocks totally different from each other but with the same previous hash

**Tags:** blockchain


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## 1 answers

### Answer by username_1 on 2019-02-20. Score: 3

> Can two blocks have the same Previous hash after being created.

Yes, two otherwise valid blocks could be created that both link to the same parent block, but importantly: **only one of those two blocks will become a part of the valid chain**. So ultimately, only one of them will be valid, and the winner will be the block that miners build on top of first (and thus it becomes a part of the longer chain).

The other block will become what is called an ['orphan block'](https://bitcoin.stackexchange.com/questions/5859/what-are-orphaned-and-stale-blocks) (though some people prefer the more exact term, 'extinct block').

You can look through the [orhpaned-blocks](/questions/tagged/orhpaned-blocks "show questions tagged 'orhpaned-blocks'") tag for more info.

> **Comments:**
> **username_0**: What happens to the transactions on the orphan block?  
> **username_1**: @username_0 simply: they are no longer a part of the blockchain record.  
> **username_0**: So that money is gone for good? The money X person sent to z person no longer exists?  
> **username_1**: @username_0 no, the bitcoin would still exist, but the transaction sending it from X->Z would not (unless that transaction is also confirmed in the longest valid chain).  
> **username_0**: Oh okay, so you would have to send the transaction again so Z can get it  
> **username_2**: @username_0: In fact, other miners will normally consider transactions from the orphan block for inclusion in future blocks on the main chain.  So the sender typically doesn't have to do anything except wait a little longer for confirmation.  

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