Double earth on metal case light fitting Qld?
My copy of ASNZS3000:2007 has no references to 'double earth', and a cursory web search finds no useful results.

I suspect your electrician is confused (or has confused you) between 'double insulation' and 'earthing', both of which are valid but mutually exclusive means of protection against electric shock.

Most pendant lights in New Zealand, which has a similar regulatory regime to Australia, are double insulated and do not require an earth. Some electricians are not particularly comfortable with this, and he may want to earth them anyway, but this is not legally required provided they comply with the correct standards and marking.

I suggest finding another electrician.