Magento 2 File Upload Issue with Multiple Fields in Admin side

I have two fields in admin side form. Logo and brand_product_image. I am using following code to upload file and save in database.

$fields = array('logo','brand_product_image');

                foreach($fields as $field):
                     $uploader = $this->_objectManager->create(
                        'Magento\MediaStorage\Model\File\Uploader', ['fileId' => $field]
                );
                $uploader->setAllowedExtensions(['jpg', 'jpeg', 'gif', 'png']);
                /** @var \Magento\Framework\Image\Adapter\AdapterInterface $imageAdapter */
                $imageAdapter = $this->_objectManager->get('Magento\Framework\Image\AdapterFactory')->create();
                $uploader->setAllowRenameFiles(true);
                $uploader->setFilesDispersion(true);
                /** @var \Magento\Framework\Filesystem\Directory\Read $mediaDirectory */
                $mediaDirectory = $this->_objectManager->get('Magento\Framework\Filesystem')
                        ->getDirectoryRead(DirectoryList::MEDIA);
                $result = $uploader->save($mediaDirectory->getAbsolutePath('brand'));
                if ($result['error'] == 0) {
                    $data[$field] = 'brand' . $result['file'];
                }
                endforeach;

When i am saving data m not getting value of brand_product_image. But i if remove logo from $fields array i am getting value of it.

Please provide some solution.