Find duplicate field values in ArcGIS using VB & Python script code

1)    Create new field “Short Integer” type to your attribute table (Example= “Duplicate”

2)    Open the field calculator for the newly created field

3)    Select VB script Parser for VB code and Python Parser for Python code.

4)    Check “show codeblock” option, while checking “show codeblock” box a new text box open at below i.e. to assign output variables.

5)    Paste the following code into the “Pre-Logic VBA Script Code” text box

VB Script

Static a As Object
Static i As Long
Dim pDuplicate As Integer
Dim pField

pField = [Test] ***(you can choose your field)
If (i = 0) Then 
Set a = CreateObject ("Scripting.Dictionary") 
End If 
If (a.Exists(CStr(sField))) Then 
pDuplicate = 1 
Else 
a.Add CStr(sField), 1 
pDuplicate = 0 
End If 
i = i + 1 

 And in the box at the bottom, insert….

pDuplicate

Python Script

uniqueList = [] 
def isDuplicate(inValue): 
  if inValue in uniqueList: 
    return 1 
  else: 
    uniqueList.append(inValue) 
    return 0

And in the box at the bottom, insert

 isDuplicate( !your field name! )