While concurrent request is hitting to API it started to save duplicate record rather than checking condtion of duplicate record
    MySampleDataSummary mySampleData = new MySampleDataSummary();  
    mySampleData.userid = id;      
    mySampleData.clientId = tokenId;
    mySampleData.remarks = "remarks here for testing";  
    mySampleData.mobile = "0123456789";
    mySampleData.approvedBy = "test user";
    mySampleData.approvalStatus = true;
    mySampleData.approvalDate = "2019-11-28";   
    mySampleData.isListed = true;
    db.dbMySampleDataSummary.Add(mySampleData);