duplicate <layer> in xml

[knutole]

<Layer> appears twice. No need for it (although it gives no unexpected behavior).

<Map srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over" buffer-size="128">
  <Style name="layer" filter-mode="first">
    <Rule>
      <RasterSymbolizer opacity="1"/>
    </Rule>
  </Style>
  <Layer name="layer" srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over">
    <StyleName>layer</StyleName>
    <Datasource>
      <Parameter name="asynchronous_request">true</Parameter>
      <Parameter name="dbname">vkztdvcqkm</Parameter>
      <Parameter name="extent">402864.106950032 7884480.78770223,1373209.1869689 9401672.88315546</Parameter>
      <Parameter name="geometry_field">rast</Parameter>
      <Parameter name="host">postgis</Parameter>
      <Parameter name="max_async_connection">10</Parameter>
      <Parameter name="password">docker</Parameter>
      <Parameter name="srid">3857</Parameter>
      <Parameter name="table">file_dbmsllgyerkxatfldqvs</Parameter>
      <Parameter name="type">pgraster</Parameter>
      <Parameter name="user">systemapic</Parameter>
    </Datasource>
  </Layer>
  <Layer name="layer" srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over">
    <StyleName>layer</StyleName>
  </Layer>
</Map>

[knutole]

map.toXML() pre-cartoRenderer:

<?xml version="1.0" encoding="utf-8"?>
<Map srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over" buffer-size="128">
  <Layer name="layer" srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over">
    <StyleName>layer</StyleName>
    <Datasource>
      <Parameter name="asynchronous_request">true</Parameter>
      <Parameter name="dbname">vkztdvcqkm</Parameter>
      <Parameter name="extent">402864.106950032 7884480.78770223,1373209.1869689 9401672.88315546</Parameter>
      <Parameter name="geometry_field">rast</Parameter>
      <Parameter name="host">postgis</Parameter>
      <Parameter name="max_async_connection">10</Parameter>
      <Parameter name="password">docker</Parameter>
      <Parameter name="srid">3857</Parameter>
      <Parameter name="table">file_upexsvwtsrzrgmhclxlq</Parameter>
      <Parameter name="type">pgraster</Parameter>
      <Parameter name="user">systemapic</Parameter>
    </Datasource>
  </Layer>
</Map>

XML created by cartoRenderer:

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE Map[]>
<Map srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over">

<Style name="layer" filter-mode="first">
  <Rule>
    <RasterSymbolizer opacity="1" />
  </Rule>
</Style>
<Layer name="layer"
  srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over">
    <StyleName>layer</StyleName>  </Layer>

</Map>

So it seems the double layer is simply a result of concat of existing xml and added xml.

[knutole]

We'll get our hands dirty with multiple layers with https://github.com/systemapic/wu/issues/331, so deferring this until then.