title: akka issue Substream Source(EntitySource) cannot be materialized more than once
body: <p>I have this error when I try to do an unmarshal twice to the response, this is because I need the response as case class and I also need it as the json-string because with the object I use it in a first-flow and the json-string in another second-flow so that's why I need both.</p>
  <p>error log:</p>
  <pre><code>21:08:16.174 [Extractor-akka.actor.default-dispatcher-14] DEBUG akka.actor.RepointableActorRef - Aborting tcp connection to api.clickup.com:443 because of upstream failure: java.lang.IllegalStateException: Substream Source(EntitySource) cannot be materialized more than once
  akka.stream.impl.fusing.SubSource$$anon$11.createMaterializedTwiceException(StreamOfStreams.scala:833)
  akka.stream.impl.fusing.SubSource$$anon$11.&lt;init&gt;(StreamOfStreams.scala:804)
  </code></pre>
  <p>code:</p>
  <pre><code>Http().singleRequest(HttpRequest( method = GET ,uri = s&quot;https://api.xxxxxx.com/task?archived=false&amp;page=${pag}&amp;subtasks=true&amp;include_closed=true&quot; )
          .withHeaders(RawHeader( CLICKUP_AUTH, config.token )))
        .flatMap {
          res =&gt;
            val bodyString:Future[String] = Unmarshal(res).to[String]
            val tasks: Future[TasksItem] = Unmarshal(res).to[TasksItem]
  
            (tasks zip( bodyString)).map{
              case (a,b) =&gt;
                TaskUnmarshall( a, b)
            }
        }
  </code></pre>
  <p>How can i unmarshal twice a single response from akka streams and get both ?</p>