Hi Daniel --
Go Button does automatically discard duplicate OSC messages received within a 0.2 second window. The messages need to have arrived from the same client (IP address + port) and that client needs to have sent no other messages in-between (e.g. no repeat `/connect` message between your hit trigger messages).
You are right that "Cue List Double-Tap Protection" won't work for what you need. That setting only guards against physical on-screen taps. There is also "Min. Seconds Between Each GO", but that applies to just a GO, which means only the cue list and not hits.
Go Button does listen on TCP. If you are finding your UDP connection unreliable, are you able to send your messages with TCP instead and then only send each message once?
Brent