Hello Rob
In the second photo have a look at the 4 ribs next to the deck that end short of the outwale while the others next to them are longer.This is typical -the short ribs leave space for the deck,are they present on the other side?.If so I would suggest that yes the deck has been replaced.Is there a notch for a coaming in the outwale could also suggest a past deck.
Where do you always find these all wood canoes?
Dan