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

Sydney's public sector holds tens of millions of digital image files across agencies ranging from the City of Sydney Council to Transport for NSW and the NSW Department of Planning. A significant share of those files are duplicates — redundant copies generated by bulk uploads, database migrations and years of siloed record-keeping. The problem has moved from a storage nuisance to a governance issue, as agencies under pressure to digitise planning records, heritage registers and development applications find their systems slowed and their data integrity questioned.

The timing matters. The NSW government's push to accelerate housing approvals — a central political priority for Premier Chris Minns — depends on digital planning portals running cleanly and quickly. Duplicate imagery in the NSW Planning Portal, which processes development applications from Penrith to Parramatta Road, can trigger duplicate entries, stalled submissions and manual intervention by assessors. The Digital Restart Fund, established by the NSW government to modernise government technology, has flagged data deduplication as a priority category in its most recent investment guidance, published in early 2025.

What Sydney Is Actually Doing

The City of Sydney Council's library and archives service, based at the Customs House site on Alfred Street in the CBD, has been running an active deduplication audit across its photographic collections since mid-2024. The project targets the council's heritage image holdings, which document everything from the demolition of old terraces in Surry Hills to the construction of Green Square town centre. A separate program at the State Library of NSW on Macquarie Street, part of its ongoing digital preservation work, has been applying automated hash-comparison tools — software that assigns each image a unique fingerprint and flags matches — to collections ingested during COVID-era digitisation drives in 2020 and 2021.

The Property Council of Australia, which represents major commercial landlords and developers active across the Sydney CBD and Western Sydney growth corridors, has noted internally that duplicate listing images on platforms tied to major property portals inflate search index sizes and distort analytics used to track market activity. Domain, headquartered in Sydney, has previously disclosed that its platform processes millions of property image uploads annually, and the company has invested in machine-learning tools to catch duplicate and near-duplicate files before they reach live listings.

How Sydney Compares With Other Cities

London's Government Digital Service published guidance in 2023 requiring all central government departments to run deduplication checks before migrating image assets to the new Crown Hosting data infrastructure. The Netherlands' Rijksdienst voor het Cultureel Erfgoed — the national heritage agency based in Amersfoort — has been operating a federated image deduplication standard across Dutch municipal archives since 2022, linking Amsterdam, Rotterdam and Utrecht onto a shared schema. Toronto City Archives completed a structured deduplication project across its 1.4 million digitised photograph holdings in 2024, reducing stored file volume by a publicly reported 23 percent.

Sydney has no equivalent city-wide standard. Each agency — the council, the State Library, Transport for NSW, the planning department — runs its own tools on its own schedule. That fragmentation is common among Australian cities, and puts Sydney behind not just European capitals but also comparable Commonwealth cities such as Auckland, where Land Information New Zealand implemented a national image metadata standard in 2023. The absence of a mandated cross-agency deduplication protocol in NSW means savings achieved in one department can be offset by redundancy growing unchecked in another.

For residents and businesses dealing with councils and planning portals day-to-day, the practical effect shows up in slow portal load times, duplicate attachments on DA submissions and occasionally mismatched heritage photos attached to the wrong parcels of land — a real risk when a Paddington terrace owner lodges a modification and the system returns imagery from a neighbouring property. The fix is not complicated in principle: standardised file-naming conventions, hash-based deduplication on ingest, and a shared metadata schema across NSW government image repositories. What it requires is coordination — and a budget line in the next Digital Restart Fund round, expected to be announced before the end of 2026.