In this case it would be better create a new data source for 'Content' so that you can use it only for the module sitemap and exclude elements as you prefer using the exclusions dropdowns in the 'Content' data source settings.

To enable the copy of data source ' Content ' to have multiples you have to enable the parameter in the picture below, in the list of data sources the checkbox will be shown beside the 'Content' to be selectable and to be duplicated.