Yes you can.Interesting! So, depart Heysham Port -> Morecambe (Platform 2 - Change ends) -> Bare Lane (Platform 2) -> Carnforth (Platform 2 - Change ends) -> arrive Lancaster (Platform 4?)
As the train to/from Heysham Port originates from Lancaster, could you legitimately do the round trip via Carnforth on a £4.50 CDR ?