user137758: this is certainly my lack of understanding, but it challenge what i know about blockchain.
I created a new address p2wpkh from public key with bech32 (testnet)  on ‎2022-11-10
: tb1q9ctu2t7zqvlevcamga9dfdhvlpeh93qdz6aawk
Made one transaction on 2022-11-10 10:29
pseudo code
b_pubkey = bytes.fromhex(pubkey)
h160 = hash_160(b_pubkey)
segwit_hrp = 'tb'
encoding = Encoding.BECH32 
address = bech32_encode(encoding, segwit_hrp, [0] + convertbits(h160, 8, 5))

But in mempool it shows it has 3 transactions, goes back to ‎2022-11-07 15:10
https://mempool.space/testnet/address/tb1q9ctu2t7zqvlevcamga9dfdhvlpeh93qdz6aawk
aren't addresses supposed to be unique and collision resistant  ?

user13866: 
I created a new address p2wpkh from public key


public key of existing address,

If you use the same public key as your starting point, you'll just generate the same address.
To create new addresses you need to first derive a new public key using the Hierarchical Deterministic (HD) process described by BIP-32.
(This answer is Community Wiki since it is just a summary of comments with the aim of removing this question from the list of unanswered questions)

137758: <p>this is certainly my lack of understanding, but it challenge what i know about blockchain.</p>
<p>I created a new address p2wpkh from public key with bech32 (testnet)  on ‎2022-11-10
: tb1q9ctu2t7zqvlevcamga9dfdhvlpeh93qdz6aawk
Made one transaction on 2022-11-10 10:29</p>
<p>pseudo code</p>
<pre><code>b_pubkey = bytes.fromhex(pubkey)
h160 = hash_160(b_pubkey)
segwit_hrp = 'tb'
encoding = Encoding.BECH32 
address = bech32_encode(encoding, segwit_hrp, [0] + convertbits(h160, 8, 5))
</code></pre>
<p>But in mempool it shows it has 3 transactions, goes back to ‎2022-11-07 15:10
<a href="https://mempool.space/testnet/address/tb1q9ctu2t7zqvlevcamga9dfdhvlpeh93qdz6aawk" rel="nofollow noreferrer">https://mempool.space/testnet/address/tb1q9ctu2t7zqvlevcamga9dfdhvlpeh93qdz6aawk</a></p>
<p>aren't addresses supposed to be unique and collision resistant  ?</p>
 13866: <blockquote>
<p>I created a new address p2wpkh from public key</p>
</blockquote>
<blockquote>
<p>public key of existing address,</p>
</blockquote>
<p>If you use the same public key as your starting point, you'll just generate the same address.</p>
<p>To create new addresses you need to first derive a new public key using the Hierarchical Deterministic (HD) process described by BIP-32.</p>
<p><sub>(This answer is Community Wiki since it is just a summary of comments with the aim of removing this question from the list of unanswered questions)</sub></p>
