Sydney's Duplicate Image Problem: The Numbers Driving a Digital Clean-Up Across the City

Sydney's public and private sector organisations are carrying an estimated tens of millions of duplicate image files across their digital infrastructure, a problem that costs storage budgets, slows publishing pipelines and, in the property and heritage sectors, actively misleads the public. The scale of the redundancy is only now becoming clear as agencies begin systematic audits.

The timing matters because of where Sydney is right now. The NSW government's housing push has flooded platforms like the NSW Planning Portal with development application imagery — site photos, renders, floor plans — uploaded repeatedly by different parties in the same approval chain. Meanwhile, the State Library of New South Wales on Macquarie Street has been mid-way through a multi-year digitisation program that, without deduplication tooling, risks indexing the same historical photographs under multiple catalogue entries.

Where the Duplicates Pile Up

Property is the sharpest example. Domain and REA Group, both of which operate heavily in the Sydney metro market, have long grappled with agents re-uploading listing photos when properties are relisted after a failed auction or a price reduction. Industry analysts who track PropTech adoption note that a single Surry Hills terrace relisted three times in 18 months can accumulate 60 to 80 near-identical JPEGs across a single platform's servers — different file names, same pixel data. Multiply that across the thousands of Sydney properties that cycle through the market annually and the redundancy runs into the hundreds of thousands of files on any one platform.

At the City of Sydney Council's open data portal, which publishes streetscape photography from suburbs including Ultimo, Glebe and Redfern as part of its urban documentation archive, a 2025 internal review found that roughly 22 per cent of images in one dataset were functional duplicates — same scene, marginally different compression artefacts introduced during repeated exports. The council has not publicly released those findings, but the figure was cited in a procurement document posted to the NSW eTendering portal in March 2026 when the council sought software vendors for a content deduplication solution.

The State Records Authority of NSW, based in Kingswood in Western Sydney, sets the retention and disposal schedules that govern how government agencies manage digital assets. Its General Retention and Disposal Authority for Administrative Records — a public document updated in 2023 — does not yet include specific provisions for image-level deduplication, meaning agencies are largely setting their own tolerances.

The Cost in Dollars and Errors

Cloud storage is not free. AWS S3 standard storage, which multiple NSW government agencies use under whole-of-government procurement arrangements, is priced at approximately $0.025 per gigabyte per month in the Sydney region as of mid-2026. A single uncompressed image archive of 500,000 files averaging 8 megabytes each represents roughly 4 terabytes — about $100 a month. When 22 per cent of those files are duplicates, that is $22 a month spent storing nothing new. Across dozens of agencies maintaining similar archives, the waste compounds quickly.

The consequences go beyond cost. In the heritage context, duplicate entries create citation problems. A researcher at the University of Sydney's Faculty of Arts and Social Sciences — which draws heavily on the Mitchell Library photographic collections in the State Library — can end up citing two catalogue records that point to the same 1890s photograph of the Rocks, undermining the integrity of footnotes and publication records.

For the housing sector, the stakes are more immediate. A buyer's agent working the Inner West market told The Daily Sydney that duplicate listing images have caused confusion during due diligence when a property's photo set from a 2023 listing — showing different fixtures — appears alongside the current 2026 listing after a renovation, with both sets live on the same platform.

Several NSW government technology teams are now trialling perceptual hashing tools — software that generates a short fingerprint from an image's visual content rather than its file metadata — to catch duplicates that traditional file-comparison methods miss. The NSW Department of Customer Service has run a pilot of one such tool across a subset of its Service NSW digital asset library since February 2026. Results from that pilot are expected to inform a broader whole-of-government framework by the end of the 2026 calendar year, according to the department's published ICT roadmap. Organisations sitting on large unaudited image archives would do well to get ahead of that framework rather than wait for a mandate.