数据实体插入:已经添加了具有相同键的项

我知道这个问题已经被问过很多次了，在浏览了帖子之后，我相信它与实体名称有关，但我对数据实体模型完全陌生，在试图用博客详细信息插入博客条目时，我遇到了这个问题。

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.ArgumentException: An item with the same key has already been added.
Source Error:
Line 365:    public void AddToblogs(blog blog)
Line 366:    {
Line 367:        base.AddObject("myblogs", blog);
Line 368:    }
Line 369:

Source File: C:'Inetpub'int422_113b16'webcontent'App_Code'blogModel.cs    Line: 367
Stack Trace:
[ArgumentException: An item with the same key has already been added.]
   System.ThrowHelper.ThrowArgumentException(ExceptionResource resource) +52
   System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add) +9382923
   System.Data.Metadata.Edm.ObjectItemAttributeAssemblyLoader.LoadRelationshipTypes() +661
   System.Data.Metadata.Edm.ObjectItemAttributeAssemblyLoader.LoadTypesFromAssembly() +17
   System.Data.Metadata.Edm.ObjectItemAssemblyLoader.Load() +25
   System.Data.Metadata.Edm.ObjectItemAttributeAssemblyLoader.Load() +4
   System.Data.Metadata.Edm.AssemblyCache.LoadAssembly(Assembly assembly, Boolean loadReferencedAssemblies, ObjectItemLoadingSessionData loadingData) +160
   System.Data.Metadata.Edm.AssemblyCache.LoadAssembly(Assembly assembly, Boolean loadReferencedAssemblies, KnownAssembliesSet knownAssemblies, EdmItemCollection edmItemCollection, Action`1 logLoadMessage, Object& loaderCookie, Dictionary`2& typesInLoading, List`1& errors) +166
   System.Data.Metadata.Edm.ObjectItemCollection.LoadAssemblyFromCache(ObjectItemCollection objectItemCollection, Assembly assembly, Boolean loadReferencedAssemblies, EdmItemCollection edmItemCollection, Action`1 logLoadMessage) +316
   System.Data.Metadata.Edm.ObjectItemCollection.ImplicitLoadAssemblyForType(Type type, EdmItemCollection edmItemCollection) +84
   System.Data.Metadata.Edm.MetadataWorkspace.ImplicitLoadAssemblyForType(Type type, Assembly callingAssembly) +151
   System.Data.Objects.ObjectContext.AddObject(String entitySetName, Object entity) +211
   blogEntities.AddToblogs(blog blog) in C:'Inetpub'int422_113b16'webcontent'App_Code'blogModel.cs:367
   BlogManager.BlogAdd(String title, String content, String userName) in C:'Inetpub'int422_113b16'webcontent'App_Code'BlogManager.cs:27
   Project_Admin_create_post.post_Click(Object sender, EventArgs e) in C:'Inetpub'int422_113b16'webcontent'Project'Admin'create-post.aspx.cs:25
   System.Web.UI.WebControls.Button.OnClick(EventArgs e) +118
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +112
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5563

BlogManager.cs

public class BlogManager
{
    private blogEntities _dbEnt = new blogEntities();
    public BlogManager()
    {
    }
    public void BlogAdd(int numId, string title, string content,string userName) 
    {
        blog newPost = new blog();
        newPost.blog_id = 1;
        newPost.blog_title = title;
        newPost.blog_content = content;
        newPost.date_created = null;
        newPost.user_name = userName;
        _dbEnt.AddTotheblog(newPost);
        _dbEnt.SaveChanges();
    }
    public class NameNotUniqueException : Exception
    {
        public NameNotUniqueException(string msg = "INT422 ERROR: matching data already exists")
            : base(msg)
        { }
    }
}

create-post.cs

public partial class Project_Admin_create_post : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (IsPostBack)
        {
            blogStatus.Text = "Your post is published";
            title.Enabled = false;
            content.Enabled = false;
        }
    }
    protected void post_Click(object sender, EventArgs e)
    {
        string _userName = User.Identity.Name;
        BlogManager blogMgr = new BlogManager();
        blogMgr.BlogAdd(title.Text, content.Text, _userName);
    }
}