Hey MGustav - welcome to the forum.
I think you are talking about a string of static transports allowing land units to jump from one to the next?
In which case - that is not how it works. In a single turn a nation can load land units on to a transport. The transport can move up 2 sea zones. Then the land units can disembark into a coastal territory.
The tanks having two moves is therefore irrelevant. The transport has two moves which it can use for land units of any type regardless of the movement value of each land unit type.
Of course if the transport does not need to move for a land unit to load and unload, for example from the UK to Western Europe, you have a static transport effecting a “bridge”.
Otherwise you might have transport(s) at each end of a sea journey moving backwards and forwards to deliver a constant stream of reinforcements.