Systems and method are provided for fraud detection and user account deduplication. One method includes receiving a request from a user to register a third user account; receiving user information associated with the third user account, wherein the user information comprises a second attribute; at a third time entry, modifying the first data store by: searching the plurality of first entries in the first data store; comparing the second attribute to the first attribute of each first entry; determining that at least one first entry comprises a first attribute that is identical to the second attribute; adding second and third entries, wherein the second entry comprises the first and third user accounts, the second attribute, and the first and third time entries; and the third entry comprises the second and third user accounts, the second attribute, and the second and third time entries.