Good Morning JoC,
This is the response from the lady who looks after your tour,
Passengers don't need to switch bags over. Passengers are entitled to 2 x pieces of luggage so one for safari (holdall) and one for beach. Beach suitcase will be stored at the suppliers office whilst they are on safari and then they are re-united with this after the safari! Medium sized soft sided holdhall needed for safari as they need to fit in small safari vehicles.
I hope this helps,
Ben