A project can definitely have more than one priority. However, in these projects, it is best to determine the order of those priorities (which one is more important and such) so that proper allocation of resources can be done at the same time. When deadlines come and time is short, there may be several priorities, however that which is most critical should be delivered first. This has been the case when on a project with team members from different plant locations: we had conveyed certain products in the manufacturing schedule to all be priority. They pushed back and wanted to know the order of priorities before starting work so that the things needed first would be done first. So even though several items were priority items, a plan to manage the order of those priorities had to be made.