Some context would probably be useful:
http://bitcoinist.net/bitbet-falls-victim-to-strange-bitcoin-double-spend-behavior/
Quote
Double-spending in the Bitcoin world is becoming a very rare occurrence, but that doesn’t mean it is impossible to pull off this type of attack. BitBet, an online gambling platform, fell victim to such an attack earlier today as a result of several of their transactions not being included in the Bitcoin Node mempool. This entire situation is sparking a lot of debate and conspiracy theories as to why one particular transaction was broadcasted twice on the network, although it is rather a stretch to claim malicious intent at this stage.
...
This fifth Bitcoin transaction used different inputs, yet the same outputs as all of the four previous transactions. Lo and behold, this transaction was picked up by Bitcoin nodes rather quickly and confirmed within thirty minutes. The issue got finally sorted, and the winners got their payouts as promised, albeit with a slight delay.
Imagine their surprise when they received a second transaction shortly afterwards, which was the very first transfer sent by BitBet. That transfer had gone unconfirmed for close to a week now, and suddenly got broadcasted by Bitcoin Nodes. It remains unknown as to why this transaction was re-broadcasted, or who was responsible for this event, but it has cost BitBet a fair amount of money.
...
This fifth Bitcoin transaction used different inputs, yet the same outputs as all of the four previous transactions. Lo and behold, this transaction was picked up by Bitcoin nodes rather quickly and confirmed within thirty minutes. The issue got finally sorted, and the winners got their payouts as promised, albeit with a slight delay.
Imagine their surprise when they received a second transaction shortly afterwards, which was the very first transfer sent by BitBet. That transfer had gone unconfirmed for close to a week now, and suddenly got broadcasted by Bitcoin Nodes. It remains unknown as to why this transaction was re-broadcasted, or who was responsible for this event, but it has cost BitBet a fair amount of money.
very strange situation indeed.
