user34455: Since the addresses are hashes of a public portion of a public/private ECDSA keypair, what would happen to two different people with different keys that hashes into the same address?
How would transactions to those addresses be handled?

user15073: As @Meni answered, both people would have access to the funds.
To illustrate how unlikely this is to ever happen, consider the following simple attack:
while True:
    genereate new keys and address
    if address has funds:
        transfer to ME

This attack can scan through an astronomical number of addresses each day. And it is so simple, anyone can carry it out and get rich! Except that it doesn't work. If it did, the bitcoin network would quickly collapse.
The reason it doesn't work is that the address space is so big, it is extremely unlikely for a collision to ever happen purely by chance (bugs in random generators are a different story...).

user575: Both people would have access to any funds in the address. Whoever is first to spend these funds wins.
Of course, it is extremely unlikely that there will be such a collision.

34455: <p>Since the addresses are hashes of a public portion of a public/private ECDSA keypair, what would happen to two different people with different keys that hashes into the same address?
How would transactions to those addresses be handled?</p>
 15073: <p>As @Meni answered, both people would have access to the funds.</p>

<p>To illustrate how unlikely this is to ever happen, consider the following simple attack:</p>

<pre><code>while True:
    genereate new keys and address
    if address has funds:
        transfer to ME
</code></pre>

<p>This attack can scan through an astronomical number of addresses each day. And it is so simple, anyone can carry it out and get rich! Except that it doesn't work. If it did, the bitcoin network would quickly collapse.</p>

<p>The reason it doesn't work is that the address space is so big, it is <strong>extremely</strong> unlikely for a collision to ever happen purely by chance (bugs in random generators are a different story...).</p>
 575: <p>Both people would have access to any funds in the address. Whoever is first to spend these funds wins.</p>

<p>Of course, it is extremely unlikely that there will be such a collision.</p>
