Sydney's Duplicate Image Problem: How the City Stacks Up Against London, Singapore and Toronto

Sydney's land registries, government property databases and major real estate platforms are carrying tens of thousands of duplicate images — the same photograph filed under multiple addresses, titles or asset records — and the scramble to clean them up is exposing gaps in the city's digital infrastructure that comparable cities began fixing years ago.

The problem has moved to the front of conversations among local government IT teams, property data managers and archivists this year, driven partly by the rollout of automated AI-cataloguing tools that flag redundant files at a scale human reviewers never could. As Western Sydney's housing pipeline accelerates — with the Bradfield City Centre precinct alone projected to accommodate tens of thousands of residents over the next two decades — accurate, deduplicated visual records are increasingly tied to legal title searches, insurance assessments and planning approvals.

What Sydney Is Actually Doing About It

The NSW Spatial Services division, which sits inside the Department of Customer Service and maintains the state's foundational geographic and property datasets, began a structured deduplication audit of its imagery holdings in late 2025. The work focuses on aerial and cadastral photography stored across legacy systems, some of which date to digitisation projects from the early 2000s. Parramatta City Council has separately identified duplicate asset photographs inside its infrastructure management system — a recurring issue for councils that manage large volumes of road, drainage and park imagery captured by contractors across different reporting periods.

On the commercial side, Domain Group and REA Group, which between them handle the bulk of Australian residential property listings, both use automated hash-matching to catch identical image files before they publish. REA Group's engineering team documented the deduplication process publicly in 2023, noting that listing image libraries can carry duplication rates above 15 percent when agents reuse photography across relisted properties. Neither company has disclosed current figures.

The City of Sydney's open data portal, accessible at data.cityofsydney.nsw.gov.au, lists dozens of spatial and photographic datasets, several of which carry known version-control issues flagged in community feedback threads still open as of this month. The Mitchell Library on Macquarie Street, which holds one of the most significant photographic archives in the southern hemisphere, completed a major digitisation deduplication pass across its Glass Plate collection in 2024 — a project that took 18 months and identified roughly 4,200 duplicate or near-duplicate image entries across its catalogue.

How That Compares to London, Singapore and Toronto

London's Ordnance Survey completed a root-and-branch deduplication of its MasterMap imagery layers in 2022, integrating hash-based matching directly into the ingest pipeline so duplicates are caught at the point of upload rather than retrospectively. The result, documented in Ordnance Survey's annual data quality report, was a 23 percent reduction in redundant records across its urban tile sets — a benchmark Sydney's equivalents have not publicly matched.

Singapore's SLA, the Singapore Land Authority, went further, mandating a single national imagery repository for all government agencies in 2021, which structurally eliminates the siloed duplication that plagues cities where multiple departments maintain separate archives. Toronto's open government team published a deduplication framework for municipal datasets in 2023 through its Open Data Toronto program, offering methodology that smaller councils in the Greater Toronto Area could adopt for their own records — a model that has no direct equivalent in greater Sydney's fragmented local government structure, which covers 33 separate councils.

That fragmentation is the core of Sydney's challenge. Without a centralised mandate equivalent to Singapore's or a shared technical standard like Toronto's framework, each of the 33 councils, plus state agencies, plus commercial platforms, manages the problem independently. Progress is real but uneven.

Property managers, archivists and councils dealing with duplicate image records in Sydney can access guidance through the NSW State Archives and Records Authority, which publishes digital preservation standards online. Agencies running large imagery libraries should request a current copy of the SARA digital recordkeeping framework — updated in 2025 — before beginning any deduplication project, as it sets out legal obligations for record disposal that affect which duplicates can legally be deleted and which must be retained as version history.