Light wiring confusion
It seems that in Oz, ordinary folk are not trusted to make electrical connections ...
According to OzLighting.com

Whilst the laws do vary slightly between the different states in Australia, it is clear that only licensed professionals are authorised to install new light fittings in your home.
Lights that are classified as “DIY” generally do not require an electrician. For example, you can buy a DIY Pendant light that has a batten-fix attachment at the end of the cord. This is designed to connect directly to your batten-fix lampholders in your ceiling, the same way as you would install a globe into these lampholders.

According to some installation instructions for a Hamilton lamp


This fitting is a DIY (Do It Yourself) product, no
electrical wiring connection or disconnection is required.
The service of a licensed electrician is not required.
This fitting is designed to be used with a batten
holder (not included).
The installation location must have an existing bat
ten holder (not included) pre-installed.
If you don’t have a batten holder (not included), please contact your licensed electrician.



A Batten-Fix Lamp-Holder from the Bunnings mothership


Before I blow something up can anyone give me advice on what to do with the second neutral?

Meekly show it to your licenced electrician as you hand over a large bundle of Boonies.
You could, as a matter of scientific interest only, edit your question to include some good sharp photos of the wires, the old lamp and the new one. You might then get some suggestions for what you might hypothetically do if you were allowed to do anything.
In many parts of the world, you can't 100% trust wiring colours to tell you which wires are live and which are neutral. For example, sometimes a neutral-coloured wire is used for a switched-live. Often you can work out what wire does what (and needs to go where) by carefully studying the arrangements before disconnecting everything. Otherwise you may need to use a voltage tester, carefully, to work out what wire does what.
Often, wires that are part of purchased lamps don't have specific colours because, with AC voltage and no exposed metal parts, it doesn't matter which is connected to live(line) and which to neutral.