Lee
many ways.
1. bank statements will show credits to the account if paid by the tenants to your account.
2. if you start claiming the PPOR as an investment property then OSR can match information provided on your tax return to determine whether you were eligible for the stamp duty concessions.
3. looking at other records such as drivers license details changed, changes to electoral role, electricity records, etc. Electricity is a big one. If you are paying the electricity bill then easier to argue that it is your PPOR. If someone else is paying the electricity bill then OSR may ask why. Dates of changes from your account to another persons account change be used to determine when property was moved into and out of. Telephone records are another one.
The tenants will likely change their details e.g. change their drivers license, electricity, telephone records etc and this can then be matched to an address. if there are duplicates then questions can be asked.