SQL Server - 存储过程同时插入重复记录

Question

为什么存储过程会在重复记录中插入此SP？ 但它只是从100个案件中发生了5-6例。 此SP同时插入重复记录，其类似2-4记录。 如何避免这个问题？ 我使用ASP.Net MVC代码，并使用AJAX进行POST。 我有这样的存储过程

DECLARE 
@PromotionID nvarchar(40)='',
@LoginName nvarchar(200),
@PromotionApplyStatusID int=0,
@PromotionCode nvarchar(40)='',
@ClaimTimestamps datetime2= null,
@RemarkText nvarchar(MAX)='',
@BetIDText nvarchar(MAX)='',
@TransIDText nvarchar(MAX)='',
@ShippingAddressText  nvarchar(MAX)='',
@PrizeAmount decimal=0,
@TurnOver int=0,
@Currency nvarchar(40)='',
@result int=0,
@AccountID int=0

SET @AccountID = (SELECT AccountID FROM MemberAccount WHERE MemberID = (SELECT MemberID FROM Member WHERE WebsiteID=2 AND Member.MemberName=@LoginName))

IF EXISTS (SELECT * FROM SystemPromotionDetail WHERE PromotionID=@PromotionID AND AccountID=@AccountID AND PromotionApplyStatusID=0)
BEGIN
    DELETE SystemPromotionDetail 
    WHERE PromotionID=@PromotionID AND AccountID=@AccountID AND PromotionApplyStatusID=0
END

IF NOT EXISTS (SELECT * FROM SystemPromotionDetail WHERE PromotionID=@PromotionID AND AccountID=@AccountID AND PromotionApplyStatusID=0)
BEGIN
    INSERT INTO SystemPromotionDetail
    (
        PromotionID,
        AccountID,
        PromotionApplyStatusID,
        PromotionCode,
        ClaimTimestamps,
        RemarkText,
        BetIDText,
        TransIDText,
        ShippingAddressText,
        PrizeAmount,
        TurnOver,
        Currency
    )
    VALUES
    (
        @PromotionID ,
        @AccountID,
        @PromotionApplyStatusID,
        @PromotionCode,
        @ClaimTimestamps,
        @RemarkText,
        @BetIDText,
        @TransIDText,
        @ShippingAddressText,
        @PrizeAmount,
        @TurnOver,
        @Currency
    )
END