If you've spent an evening searching for a London flat, you'll know the feeling: you recognise the same living room, the same kitchen counter, the same slightly-too-wide-angle photo of the bedroom — but it's under a different agent's name, or on a different site, sometimes at a slightly different rent. You're not imagining it, and it isn't a glitch. It's how the portals and agency model work.
Reason one: multi-agency instructions
When a landlord wants to let a flat quickly, they can instruct several letting agents at once rather than giving it to a single agency. This is called a multi-agency (or "multiple agency") arrangement. Each agent is racing to be the one who finds a tenant, because only the agent who does the deal gets paid. From the landlord's point of view it widens the net. From your point of view, it means the same flat shows up under two, three, or even more agency names — occasionally with small differences in the rent, the photos used, or how the description is written.
Reason two: cross-portal syndication
Separately, almost every agent lists through property software that pushes a single advert out to multiple portals automatically. One instruction becomes a Rightmove listing, a Zoopla listing and an OnTheMarket listing more or less simultaneously. That's normal and expected — but it multiplies the duplication. Put the two effects together and a single flat with two agents on three portals can easily produce five or six adverts you'll scroll past.
Why this quietly wastes your search
Duplicates don't just clutter the results — they distort your sense of the market. A street can look like it has ten available flats when really it has three. You waste time re-reading listings you've already dismissed, and you risk enquiring twice on the same property through two different agents. When flats move as fast as they do in London, minutes spent re-scrolling the same advert are minutes you don't get back. (If you want to understand that speed, see why London flats disappear in hours.)
How to spot a duplicate
- Photos are the giveaway. The same rooms shot from the same angles, in the same light, almost always mean the same flat — even if the cover image is different.
- Match the specifics: bedroom and bathroom count, floor area, floor level, and any distinctive feature (a particular kitchen layout, a balcony, a specific view).
- Check the location. Portals often blur the exact address, but the street name or postcode area usually lines up across the duplicates.
- Compare the rent. The same flat at the same price under two agents is a normal duplicate. The same flat at a much lower price from a "private landlord" is a warning sign, not a bargain.
When a duplicate is actually a red flag
Most duplicates are harmless. The exception is the too-cheap copy: fraudsters lift photos and details from a genuine listing, re-post them at an attractive price, and pose as the landlord. If you find what is clearly the same flat listed normally by an agent and, separately, much cheaper by a private individual pushing you to pay a deposit fast, treat the cheap one as a likely scam. Our full guide on how to avoid rental scams in London covers exactly how to verify before you part with any money.
How FlatSignal handles duplicates
Cutting through this repetition is one of the specific problems FlatSignal (our product) is built to solve. It aggregates rental listings from the major London portals and folds duplicates of the same property — whether that's two agents, three portals, or both — into a single entry, so you see each real flat once instead of four times. It's not magic: matching is based on the details in the listings, so the occasional edge case slips through, and FlatSignal always links you back to the original portal listing to enquire. But for the common case — the same flat cloned across agents and sites — de-duplication turns a noisy, repetitive search into a much clearer picture of what's genuinely available. You can see de-duplicated listings on the live dashboard, and if you want alerts that don't spam you with the same flat repeatedly, read how to set up property alerts that actually work.