function readOnly(count){ }
Starting November 20, the site will be set to read-only. On December 4, 2023,
forum discussions will move to the Trailblazer Community.
+ Start a Discussion
Pavithra GajendraPavithra Gajendra 

Offline data sync with saleforce creates duplicate records in mobile data .

When records are created in offline mode of mobile and those records are synced with salesforce by webservices when device is online . On response its creating duplicate records in mobile data . Smartstore is used for data storage and soup methods for all DML operations .
Pavan DavePavan Dave
If this is about Salesfoce1:

- By default, duplicate rules run when users save records.
- You can change this behavior for Salesforce1 so that duplicate rules run as users complete fields on the record instead.
- This reduces data entry time, which is always desirable on a mobile device. In the full Salesforce site, from Setup, click Mobile Administration | Salesforce1 | Settings.
- In the Duplicate Rule Settings section, select Run duplicate rules when users complete fields.

Reference: 

http://releasenotes.docs.salesforce.com/en-us/winter14/release-notes/rn_mobile_salesforce1_newfeat_dedupe.htm


Pavithra GajendraPavithra Gajendra
Its about hybrid app not Salesforce1 .
Pavithra GajendraPavithra Gajendra
Duplication of records on save happens

- During offline record creation salesforce Id doesnt exist , need to use external Id to upsert in smart store . By this way in both ends duplication is prevented i.e smartstore and salesforce . 
- External Id can be a random number .