(Quoted rules have been cut down to only include “necessary” statements.)
There is a rule against a student driving under more than one team number at a single event:
There is also a rule against a team competing with more than one robot at a single event:
However, there is no rule against a robot being inspected and competing under two different team numbers.
It would be possible, however not very practical for the High School and Middle School competitions, because of the possibility that the two (or more) teams sharing the same robot would be playing matches at the same time. But in VEX U, multiple teams could swap robots between each other because of the “unlimited number of robots rule,” as long as the swapped robots are inspected under all of the swapping teams’ names.
Another possibility would be a High School or Middle School robot being inspected under a VEX U team’s name and being used by the VEX U team whenever it is not needed by the High School/Middle School team.
Am I correct in assuming that all of these scenarios would be legal?