title: XDocReport can't display two image in generated document
body: <p>I insert two image to template: "logo" and "background"
  But only background image presented in template.</p>
  
  <p>I create ImageProdiver </p>
  
  <pre><code>private IImageProvider createImageProvider(IXDocReport ixDocReport, String fieldName, Blob image) {
      FieldsMetadata metadata = ixDocReport.createFieldsMetadata();
      metadata.addFieldAsImage( fieldName);
      ixDocReport.setFieldsMetadata(metadata);
      InputStream inputStream = null;
  
      try {
          inputStream = image.getBinaryStream();
          IImageProvider logo = new ByteArrayImageProvider(inputStream);
          logo.setUseImageSize(true);
          logo.setResize(true);
          inputStream.close();
          return logo;
      } catch (SQLException | IOException e) {
          throw new GeneralException("Error reading logo");
      } finally {
          if(inputStream != null) {
              IOUtils.closeQuietly(inputStream);
          }
      }
  }
  </code></pre>
  
  <p>Create two Image provider</p>
  
  <pre><code>IImageProvider logo = createImageProdider(report, "logo", blobimage));
  IImageProvider background = createImageProdider(report, "logo", blobimagebacground));
  </code></pre>
  
  <p>and insert to context in builder</p>
  
  <pre><code>context = this.report.createContext();
  context.put("logo", logo);
  context.put("background", background);
  </code></pre>
  
  <p>after generate document, exist only background image.</p>
  
  <p>I do not understand why there is this problem, why only one picture is displayed.</p>
  
  <p>How to solve this problem?</p>