'The first group captures one or more consecutive digits.
'The second group matches a single character.
Imports System.Text.RegularExpressions
Module Example
Public Sub Main()
Dim pattern As String = "(\d+)*(\w)\2"
Dim input As String = "AA"
Dim match As Match = Regex.Match(input, pattern)
Dim group1 As Group = match.Groups.Item(1)
Console.WriteLine("Group 1 value: {0}", If(group1.Success, group1.Value, "Empty"))
Dim group2 As Group = match.Groups.Item(2)
Console.WriteLine("Group 2 value: {0}", If(group2.Success, group2.Value, "Empty"))
End Sub
End Module