This depends on the security clearance for drivers in MyGeotab. A driver can be given permission, or restricted, to add trailers to the database. 

If there is a fixed list of trailers, do not enable drivers to add trailers. Drivers will add the same trailer many times instead of search the list. This leads to significant  administrative issues. 

If drivers are using unique trailers consistently, train them to search the list before entering another trailer. You should have a process to idenfity duplicate trailer names, even if they are actually different trailers. Trailers from different companies may use the same trailer name which will be indistinguishable during an audit.