As you all know it's not very secure to send bitcoins on known addresses, some bots are watching. Could someone explain me how these bots manage to propagate several transactions of the very same transaction output in the network (ex https://blockchain.info/fr/address/1HZwkjkeaoZfTSaJxDw6aKkxp45agDiEzN) It appears there is a competition between at least 3 bots on the previous address.
For fun, I try to code a C# app building+broadcasting transaction as soon as bitcoins are received on the watched address. No chance at all. Bitcoind/blockchaininfo says this output is already spent (only 2 s after receiving it). So if there is a mechanism which prevents to add multiple transactions on the same output (before any confirmation), how did current bots do that (1LdUHTEVxWJhrhKfy4H3VuYDnTHQVjsdBn && 1aa8hSJaxa2jKFtuBYp8VBsFNofsnoBHX)???
And it seems that 1LdUHTEVxWJhrhKfy4H3VuYDnTHQVjsdBn is almost always the winner!