Macro to skip duplicates

[hlpsom1]

I have a macro that allows me to generate worksheets based on a range of cells, however if the range includes a duplicate it throws an error.
I also need to solve the problem of adding new data to the range and allowing the macro to skip over cells where a worksheet already exists and only create new worksheets for new and unique cells content.

Any ideas would be helpful.

Here is the current Macro and I am attaching a sample.

Sub Generate_worksheets()
    
 
  Dim ws1 As Worksheet
    
    Set ws1 = ThisWorkbook.Worksheets("Master")

    Dim MyCell As Range, MyRange As Range

    Set MyRange = Sheets("Select").Range("A5")
    Set MyRange = Range(MyRange, MyRange.End(xlDown))
    Sheets("Master").Visible = True
    Sheets("End").Visible = False
    For Each MyCell In MyRange
       ws1.Copy ThisWorkbook.Sheets(Sheets.Count)
      
       ThisWorkbook.Worksheets("Master (2)").Name = MyCell.Value
       
    With ActiveSheet
    .Range("B3").Value = .Name
    End With
   
   
   Next MyCell
        
        Sheets("Master").Visible = False
        Sheets("End").Visible = True
    
    MsgBox "Done!"

End Sub

Thanks in advance,
Matt