About
DupeScan was built to help out buyers of rare items. Since at least early 2025, a known exploit has been actively used to duplicate rare Dota 2 items. The community reported it, however Valve doesn't seem to have taken action on this yet. Meanwhile, traders keep getting burned, buying items at full price without knowing they're dupes.
The goal of this tool is simple: give traders a way to check before they trade. If people prefer to buy dupes, at least they should know what they're getting. The database started from public guides made by community members and is now powered by community submissions. It's public and can be exported and reused by anyone. Features like Owner History exist to help trace duplicated items, not to single someone out in particular.
This is an independent project. The free tier should be enough for most people. If you happen to need more search budget, please consider contributing, or getting a support package. Any package goes to supporting the project and its costs of running. You can see what's coming on the roadmap. Found a dupe? Consider submitting it.
Frequently Asked Questions
Learn more about how this tool works
Mass Duped (red): confirmed large-scale duplication. Duped (orange): confirmed duplicate at smaller scale. Suspect (yellow): flagged but unconfirmed. Clean (green): no signs of duplication. Low Info: report exists but insufficient data.
Reflects how well-supported a submission is. 0 = unverified. Below 10 = low. Below 20 = moderate. 20 and above = high confidence.
Asset ID is the identifier for a specific item copy. It changes on every trade or market sale. Original ID is the asset_id assigned when the item first appeared and never changes. When multiple items share the same original_id, they are duplicates. DefIndex is a numeric ID for the item type. All copies of the same item share one defindex (e.g., every Dragonclaw Hook has the same defindex). It is optional when submitting.
If you've found a duped item, you can report it through our submission form. You'll need the item's asset_id and original_id. See the contribution guide below for a step-by-step walkthrough on finding these values.
Yes, enter your Steam profile URL or SteamID64 in the search. It works the same as checking anyone else's inventory.
Submissions start as pending and go through community verification. Only verified entries are used when checking inventories.
Log in and you'll see a feedback/bug submission button. I'll try my best to answer submissions and implement requests, but keep in mind this is a side project built in my spare time.
Enter any Steam profile URL or SteamID64 into DupeScan and the tool will compare their inventory against a community-verified database of known duplicates.
Trading duped items carries significant risk. Their market value is typically much lower than clean items. Items originally worth $10K–$25K have dropped to $4K or less once identified as dupes. There is also a possibility that Valve could revoke duplicated items in the future, leaving the buyer with nothing.
Valve has the technical ability to detect and remove duplicated items, as they control the Steam platform and item databases. While they have not taken widespread action so far, the risk of future enforcement remains. This uncertainty is one of the key reasons buyers should verify items before trading.
High-value cosmetics are the primary targets for duplication. This includes rare arcanas, unusual couriers, ethereal gems, Crimson Witness items, and other collectibles worth hundreds or thousands of dollars. The higher the item's value, the more likely it has been targeted.
A clean item has a unique original_id with no other copies in existence. It is the one-of-one legitimate version. A duped item shares its original_id with one or more copies created through a Steam exploit. Both function identically in-game, but duped items carry lower market value and higher risk.
It depends on the item's rarity, how many duplicates exist, and how widely known the duplication is. Losses of 50–80% or more are common once an item is identified as duped.