That would be a misunderstanding. Gateway’s don’t invent traffic in either direction, they are just transparent translators between LoRa and IP backhaul. Whatever the problem is, it’s an issue of the contract between the node and the servers being disagreed upon or mis-implemented at at least one end.
There does appear to be a duplication issue in displayed downlinks somewhere, but as it’s not physically possible for a gateway to transmit three messages on the same frequency at the same time that cannot be a practical cause of this issue.
Further, even if duplicates did somehow get through, they would be immediately dropped as they contain already used sequence counter values.
If the node is not receiving the downlink, that could be an issue, regardless if it is caused by radio range, interference, or a gateway choking on an impossible combination of downlink requests. But the key to debugging that would be to monitor the node behavior - really, until your system is working 100% you want your nodes giving serial debug output on each transmission, and on each receive window, regardless if they find anything or not and if what they do find decodes as valid or not.