INSERT Creating 2 Identical Records

i created a simple table to record all uploaded files to my website. now, it works, but the problem is, it posts to the table 2 times, as in it executes "Button1_Click"  event twice. The result is i get two records which are the same, and only differs in primary key (because i set it as an autonumber). how do i fix this? thanks in advance

here's the code:

HTML:  <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConflictDetection="CompareAllValues"
ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
InsertCommand="INSERT INTO [Base_Files] ([User_ID], [Date_Posted], [File_Type], [File_Size], [File_Name], [File_Description]) VALUES (@User_ID, @Date_Posted, @File_Type, @File_Size, @File_Name, @File_Description)">

<InsertParameters>
<asp:Parameter Name="User_ID" />
<asp:Parameter Name="Date_Posted" />
<asp:Parameter Name="File_Type" />
<asp:Parameter Name="File_Size" />
<asp:Parameter Name="File_Name" />
<asp:Parameter Name="File_Description" />
</InsertParameters>

</asp:SqlDataSource>

 VB:Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click

If FileUpLoad1.HasFile Then FileUpLoad1.SaveAs(Server.MapPath(".") & "files" & FileUpLoad1.FileName)
Label1.Text = "Received <strong>" & FileUpLoad1.FileName & "</strong> Content Type: " & FileUpLoad1.PostedFile.ContentType & ", Length: " & FileUpLoad1.PostedFile.ContentLength & "bytes, at " & Date.Now.ToString("MMM dd, yyyy, h:mmtt")

SqlDataSource1.InsertParameters("File_Name").DefaultValue = FileUpLoad1.FileName.ToString()
SqlDataSource1.InsertParameters("User_ID").DefaultValue = User.Identity.Name.ToString()
SqlDataSource1.InsertParameters("File_Type").DefaultValue = FileUpLoad1.PostedFile.ContentType
SqlDataSource1.InsertParameters("File_Size").DefaultValue = FileUpLoad1.PostedFile.ContentLength
SqlDataSource1.InsertParameters("File_Description").DefaultValue = txtDescription.Text.ToString()
SqlDataSource1.InsertParameters("Date_Posted").DefaultValue = Date.Now.ToString("MMM dd, yyyy, h:mmtt")
SqlDataSource1.Insert()

Else
Label1.Text = "No uploaded file"
End If

End Sub