How can I forward a http request to two different URL using iRules.

So, to be clear, you want to just send a copy of the request to a second or third URL? Presumably to test new services before making them active?

The answer to that is a qualified yes. I am doing just that right now, specifically to test a new web service. For this, I had to create a "helper" virtual to handle the SSL for me. I capture the data, then play it to the helper virtual via a sideband connection (I pilfered bits from various examples on devcentral):

when RULE_INIT {
        set static::sb_vserver "helper-sideband-virtual"
}
when HTTP_REQUEST {

    Check if request was a POST
   if { [string tolower [HTTP::method]] eq "post" } {
         Connect to an external host with a connection timeout of 1000ms and an idle timeout of 30 seconds
        set conn [connect -timeout 1000 -idle 30 -status conn_status $static::sb_vserver]
         Check if connection was not established to sideband server
        if {$conn eq ""}{
                return
        }

       Check if there is a Content-Length header
      if { [HTTP::header exists "Content-Length"] } {
         if { [HTTP::header "Content-Length"] > 1048000 }{

             Content-Length over 1Mb so collect 1Mb
            set content_length 1048000
         } else {
             Content-Length under 1Mb so collect actual length
            set content_length [HTTP::header "Content-Length"]
         }
      } else {
         set content_length 1048000
       }
        Don't collect content if Content-Length header value was 0
       if { $content_length > 0 } {
          HTTP::collect $content_length
       }
    }
}

when HTTP_REQUEST_DATA {
         Get the current connection status
        if { [string tolower [HTTP::method]] eq "post" } {
                set conn_info [connect info -idle -status $conn]
                if {$static::sb_debug} { log local0. "$log_prefix Connect info: <$conn_info>" }
                 Send a TCP payload containing an HTTP request
                set data "POST /newservice HTTP/1.1\r\nUser-Agent: sideband/1.0\r\nContent-Type: application/xml; charset=utf-8\r\nHost: [HTTP::host]\r\nContent-Length: $content_length\r\n\r\n[HTTP::payload]"
                set send_info [send -timeout 3000 -status send_status $conn $data]
                close $conn
        }

}

If that's not what you are trying to do, please clarify.