System.Collections.Generic.List
Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        ' Declaring variables
        Dim generator As New Random()
        ' Create a list to store our random numbers in, just like dim storage would.
        Dim randoms As New List(Of Integer)

        While randoms.Count < 10
            Dim testNumber As Integer = generator.Next(1, 11)
            If Not randoms.Contains(testNumber) Then
                randoms.Add(testNumber)
            End If
            Debug.WriteLine(" Testing number " & testNumber)
        End While
    End Sub
End Class