Great tutorial! @DarthCoin had already mentioned this possibility, thanks for bringing it up. If you’re offline when you sign, there’s no way the offline device will ever know whether the transaction was broadcast and confirmed. There might be some restriction in the app you use to sign, but in principle there shouldn’t be, since the confirmation never reached that device.

So it doesn't matter how many times I sign, the block would only care which one I broadcast, right?

Natalia

If you have a utxo that you use in one psbt you sign but do not broadcast

and then you use the utxo in another psbt that you do not broadcast

the first one that successfully makes it into a block makes the other invalid.

You can sign as many different transactions using your utxos as you like, but nodes will only recognize the first one they see in a confirmed block.

bitcoin

One of the peace-of-mind ways to Spend from a Cold Wallet: PSBT

If you have a utxo that you use in one psbt you sign but do not broadcast

and then you use the utxo in another psbt that you do not broadcast

the first one that successfully makes it into a block makes the other invalid.

You can sign as many different transactions using your utxos as you like, but nodes will only recognize the first one they see in a confirmed block.