I’ve been searching for concrete info too.
2 different calls to RC gave me 2 different answers.
One said a second test is not necessary if you’re on the same ship for both legs, even if Canada is the second leg.
The other rep said that RC will test us 2 days before the turn around day.
Im afraid to make another call. They may tell me I have to get off the ship and find a place to get tested! 😆