dnf_module { 'module_nginx_stream_1.20':
  module         => 'nginx',
  enabled_stream => true,
}
dnf_module { 'module_nginx_stream_1.22':
  module         => 'nginx',
  enabled_stream => true,
}

That's a valid puppet code, not a valid desired state, unlike

package { 'nginx':
  ensure   => '1.20',
  provider => dnfmodule,
}
package { 'nginx':
  ensure   => '1.22',
  provider => dnfmodule,
}