c# – 在PK为Identity的表上违反PRIMARY Key(Duplicate key)？

CREATE TABLE [Snapshots].[Crashproof](
    [EmoteCountId] [int] IDENTITY(1,1) NOT NULL,[SnapshotId] [int] NOT NULL,[Emote] [nvarchar](42) NOT NULL,[EmoteCountTypeId] [int] NOT NULL,[Count] [decimal](19,6) NOT NULL,CONSTRAINT [PK_SnapshotsCrashproof] PRIMARY KEY CLUSTERED ([EmoteCountId] ASC) ON [PRIMARY],CONSTRAINT [FK_SnapshotsCrashproof_Snapshots] FOREIGN KEY ([SnapshotId]) REFERENCES [Snapshots].[Snapshots] ([SnapshotId]) ON DELETE CASCADE,CONSTRAINT [FK_SnapshotsCrashproof_EmoteCountTypes] FOREIGN KEY ([EmoteCountTypeId]) REFERENCES [dbo].[EmoteCountTypes] ([EmoteCountTypeId])
) ON [PRIMARY]
GO

以及插入其中的代码：

using (SqlBulkCopy bulkCopy = new SqlBulkCopy(connection,SqlBulkCopyOptions.Default,trans))
{
    bulkCopy.DestinationTableName = "Snapshots.Crashproof";
    bulkCopy.ColumnMappings.Add(new SqlBulkCopyColumnMapping("SnapshotId","SnapshotId"));
    bulkCopy.ColumnMappings.Add(new SqlBulkCopyColumnMapping("EmoteCountTypeId","EmoteCountTypeId"));
    bulkCopy.ColumnMappings.Add(new SqlBulkCopyColumnMapping("Emote","Emote"));
    bulkCopy.ColumnMappings.Add(new SqlBulkCopyColumnMapping("Count","Count"));

    using (IDataReader reader = ObjectReader.Create(emoteCountTypesToSnapshot))
    {
        bulkCopy.WriteToServer(reader);
    }
}

它在99.99％的时间内运行良好(并且每分钟都进行批量复制),但是我确实有一次异常,它在最后一行(bulkCopy.WriteToServer(reader);)：

Violation of PRIMARY KEY constraint…Cannot insert duplicate key in object ‘Snapshots.Crashproof’. The duplicate key value is (247125).

我知道不建议直接在最终表中批量插入,我将修改我的代码以批量插入到临时表中,然后从那里插入.但这是什么导致了这个例外？

我真的不明白如何在Identity字段上出现重复键：|