Found in T272105
When recurring donations are refunded, only the first one of the series makes it into Civi.
This is because there isn't enough information in what is sent back from Ingenico to distinguish 2+ donations on from the first one.
Need to change the SmashPig audit code and the Civi import to figure out what donation it actually is.
Looks like all the 2+ payments have 200001 instead of 100001 at the end of the gateway_txn_id