http://www.sro.vic.gov.au/sro/SROnav.nsf/v/D9C90CE2DFBAA2FACA2576AC0005E888/$file/DA-026.pdf

will give you a better explanation.
 
From what I can see though if the properties are advertised seperately and the purchase of one is not dependant on the other you will be fine.

Stamp duty savings are significant. 5 x $130000 properties seperatly is something like 14k total, one 650000 property 27k (from memory, please don't quote me )