You should not be able to add more than one instance of most blocks to your Dashboard

Test in master/311 as implementation differs Log in as admin Navigate to user dashboard Turn edit mode on/customise the page (If the Private files block is already present, then delete it) Press Add a block Press Private files Confirm Private files block is added Press Add a block Confirm Private files is not listed in the Add a block modal Press Text/HTML block Confirm Text/HTML block is added Press Add a block Confirm Text/HTML is listed in the Add a block modal Confirm you can add the Text/HTML block again