Except for short ones for single bedrooms, any poles (both wooden and metal) Ive ever put up have been joined.
Shorter poles should have 3 supports (left,right, centre) as standard so buying 2 together should give you enough supports with spacing them out as required. If wood, Id use a bit of wood glue with dowel for joining. It'll mean a bit of drilling into the pole but it should be easy enough.