Use of two robots at the competition

Hello everyone,
at last years European Robocup I saw a team, that had two seemingly identical robots, that they participated with during the competition. Additionally I read this post from 2017, which again states, that it is allowed to use two different robots at different runs of the same competition.
(Is it allowed to use two different robots at different rounds?)
On the other hand I heard, that at another international competition a team was not allowed to participate with two different Robots.
Therefore I am not entirely sure, whether it is legal or not and if yes, whether the robots have to be identical or not. Could you please clarify the current status of the rules?

Best Regards
Jonas - Team Jak&Jonas