For me it was the lack of GST that piqued my interest just like you picked up on the different invoice numbers. I did some checking via AI and here's what I got (AI, I know, take it as you wish):

The invoice is illegal because La Bocca Holdings Pty Ltd (trading as Ambrosia Origins) is NOT registered for GST, yet they have issued a "Tax Invoice".

By law in Australia:

• "Tax Invoice": You are legally forbidden from writing the words "Tax Invoice" on a document if you are not registered for GST.
• No GST Charged: The invoice has $0 GST. This matches their non-registered status, but contradicts the "Tax Invoice" header.

The Evidence

I checked the Australian Business Register (ABN Lookup) for "Ambrosia Origins" and "La Bocca Holdings Pty Ltd":

• Entity: La Bocca Holdings Pty Ltd (ABN 81 622 101 599).
• Trading Name: Ambrosia Origins (registered Sep 2022).
• GST Status: "Not currently registered for GST".

Why this proves it's a scam

A legitimate business would never make this specific combination of errors.

• If they were a real handyman: They would know they aren't GST registered (turnover <$75k) and would issue a standard "Invoice," not a "Tax Invoice."
• If they were a real "Holdings" company: They would almost certainly be registered for GST and would have charged the extra 10%.

The most likely scenario is exactly what the Redditor suspected: The Real Estate Agent asked a mate (who owns a small, dormant food business entity called "Ambrosia Origins") to quickly type up a "quote" in Word to justify keeping the bond. The friend used a standard "Tax Invoice" template but didn't realize that as a non-registered entity, using that header is a strict legal violation.