When opening a link in a message with more than one, only the first is ever selected. The same happens for attachments.
A quick workaround would entail opening ALL links/attachments, and letting the user close the ones they are not interested in at a later time.
Even better, only if multiple links/attachments are present, one could open a pop-up. The user can cycle between the options in the list with up/down, open one with "Enter", or close the list with "q". I am not sure whether the list should stay open after one entry is selected.