First Back Up your data, then try this code

Function UpdateTable()
Dim MyDB As DAO.Database, MyRec As DAO.Recordset
Dim MyCount As Integer, OldValue As String
OldValue = ""
Set MyDB = CurrentDb
Set MyRec = MyDB.OpenRecordset("Select ID from TableName Order By ID")
While Not MyRec.EOF
   If OldValue = MyRec!ID Then
       MyCount = MyCount + 1
   Else
       MyCount = 1
   End If
   OldValue = MyRec!ID
   MyRec.Edit
   MyRec!ID = MyRec!ID & Format(MyCount, "00")
   
   MyRec.Update
   MyRec.MoveNext
Wend
End Function

If you can guarantee that the Name field is unique then you could try

UPDATE YourTable
SET ID = ID & DCount("ID","YourTable","ID=""" & [ID] & """ AND [Name] <="""
& [Name] &"""")

Alternative with a limited number of  duplicated ids might be to repeat the
query below changing  the 1 to 2, 3, 4, etc.
UPDATE YourTable
SET ID = [Id] & "1"
WHERE
(SELECT Count([Name])
FROM YourTable as YT
WHERE YT.ID = YourTable.ID and YT.Name <=YourTable.Name) = 1
AND YourTable.ID Not Like "*#"

<<< add the last criteria to only update records that do not end in a
number>>> hopefully keeping you from updating records that have already been
updated.

AS always, back up your data FIRST.  There is no going back