Came across this issue a while ago and two solutions spring to mind.
1- Administrative type: Edit page properties and add header tag. Apparently the latter tag takes precedence.
2-Programmatically: Add module, skin-object, directly in skin or on default.aspx.cs (after logic for metarobots, do a chtrl find and place code after)
The logic goes any url or path you want not indexed add it to web-config e.g. <add key="MetaRobots" value="/db_lpt_1.aspx, /db_lpt_2.aspx,/join-now/ctl/" />
Example skinobject code:
Public Class _MetaRobots
Inherits SkinObjectBase
Private Shared siteExclusion As String = ConfigurationManager.AppSettings("MetaRobots")
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Try
Dim pageurl As String = String.Format("{0}://{1}{2}{3}", Context.Request.Url.Scheme, Context.Request.Url.Host, If(Context.Request.Url.Port = 80, String.Empty, ":" + Context.Request.Url.Port), Request.RawUrl)
Dim MetaRobots As System.Web.UI.HtmlControls.HtmlMeta = Me.Page.Header.FindControl("MetaRobots")
If Not (String.IsNullOrEmpty(siteExclusion)) Then
Dim noIndexFollowPages As String() = siteExclusion.Split(",")
If Not noIndexFollowPages Is Nothing Then
Dim yes = noIndexFollowPages.AsParallel().[Single](Function(x) pageurl.Contains(x))
If Not String.IsNullOrEmpty(yes) Then
If Not MetaRobots Is Nothing Then
MetaRobots.Content = "NOINDEX, FOLLOW"
End If
End If
End If
End If
Catch ex As Exception
'do nothing
End Try
End Sub
End Class