Random Duplicate Results From SSRS

Question

Hello everyone, I have a stored procedure that joins 4 tables. For more than a semester, the report is running fine until recently I got a random duplicate data. Below is my sp:

ALTER PROCEDURE [dbo].[spGet_eci_all_sales]
    -- Add the parameters for the stored procedure here
    @DateStart nvarchar(50),
    @DateEnd nvarchar(50)
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    -- Insert statements for procedure here
    SELECT ROW_NUMBER() OVER(ORDER BY E.IssuanceType) AS Ref,
    ROW_NUMBER() OVER(PARTITION BY IssuanceType ORDER BY IssuanceType) Nos,
        e.BranchCode,
        e.AgentID,
        a.AgentName,  --added December 21, 2017
        e.DateIssued,
        e.ApplicationTime,
        e.IssuanceType,
        e.MotorCINo,
        e.CustomerNo,
        c.CustomerName,
        c.Village,
        c.District,
        c.Province,
        c.CustTelephone,
        c.MobilePhone,
        c.CustEmail,
        c.TaxPayersID,
        e.VehicleType,
        e.VehicleBrand,
        e.VehicleModel,
        e.VehiclePlateNo,
        e.VehicleEngineNo,
        e.VehicleChasisNo,
        e.VehicleGrossTon,
        e.VehicleSettingCap,
        e.VehicleYearManufactured,
        e.VehicleBeganUsing,
        e.VehicleYearRegistered,
        e.VehicleUsageType,
        e.TaxStatus,
        e.InsuranceType,
        e.InsuranceOption,
        e.CompulsoryPrem,
        e.CompulsoryNCD,
        e.CompulsoryNetPrem,
        e.CoverAmount,
        e.DeductiblePercent,
        e.Deductible,
        e.OwnPrem,
        e.OwnNCD,
        e.OwnNetPrem,
        e.PeriodFrom,
        e.PeriodTo,
        e.DefenseRecourse,
        e.PersonalAccident,
        e.NetPremium,
        e.RegistrationFee,
        e.VAT,
        e.TotalPremium,
        ac.CommissionRate,
        e.AgentGrossCommission,
        e.AgentTax,
        e.AgentNetCommission,
        e.Username
    FROM     dbo.tblCustomers c INNER JOIN
             dbo.tblMotorInsurance_eCI e ON c.CustomerNo = e.CustomerNo INNER JOIN
                         dbo.tblAgentCommission ac ON e.AgentID = ac.AgentID
                         INNER JOIN dbo.Agents a ON e.AgentID = a.AgentID --added December 21, 2017

    WHERE  (e.DateIssued BETWEEN @DateStart AND @DateEnd) and e.Remarks = 'SOLD' and e.BranchCode='01'
    ORDER BY e.IssuanceType ASC
END

and below is the duplicate result:

 

Any suggestions on what went wrong? Thanks so much.