anchor.diff:                          | None -> None
                         Node = Some node } ]
   
  -    member this.DeleteOldReferences(referenceNode : ReferenceNode) =
  -        let nodes = this.GetReferences()
  -        match nodes |> Seq.tryFind (fun node -> node.DLLName = referenceNode.DLLName && node.Condition = referenceNode.Condition) with
  -        | Some targetNode -> 
  +    member this.DeleteOldReferences(name) =
  +        this.GetReferences()
  +        |> Seq.filter (fun node -> node.DLLName = name) 
  +        |> Seq.iter (fun targetNode -> 
               match targetNode.Node with
               | Some node -> node.ParentNode.RemoveChild(node) |> ignore
  -            | None -> ()
  -        | None -> ()
  +            | None -> ())
   
       member this.AddReference(referenceNode: ReferenceNode) =
           let firstNode =
  
positive.code:                         | All -> true,None
  
                      
                      if installIt then
                          let node =
                              { DLLName = lib.Name.Replace(lib.Extension, "")
                                HintPath = Some(relativePath.Replace("/", "\\"))
                                Private = true
                                Condition = condition
                                Node = None }
                          this.DeleteOldReferences node
                          this.AddReference node
  
          if Utils.normalizeXml this.Document <> this.OriginalText then
              this.Document.Save(this.FileName)
  
negative.code:         firstNode.ParentNode.AppendChild(copy) |> ignore
  
      member this.UpdateReferences(extracted,usedPackages:System.Collections.Generic.HashSet<string>) =
          for _, libraries in extracted do            
              let libraries = libraries |> Seq.toArray
              for (lib:FileInfo) in libraries do                                       
                  this.DeleteOldReferences (lib.Name.Replace(lib.Extension, ""))
  
          for package, libraries in extracted do
              if usedPackages.Contains package.Name then
                  let libraries = libraries |> Seq.toArray
  