What happens here is that the transactions are malleable.

Roughly speaking, when you send a transaction, it has some data in it which is not really relevant to the transaction. This data can be changed, and the same transaction looks slightly different.

This would not really be a problem, but the effect is that the changed transaction gets a new txid. The effect is what you observed: two transactions with different txid's which really have the same inputs and outputs.

Obviously someone is changing the transactions and broadcasting them again (for kicks, or whatever).