Is it possible to let more than one user manage an individual report?

Yes, a creator of a dashboard and report can share and deliver other users the right to modify and edit them. When owners share a dashboard for example, they can define the level of access the recipient receives, from editing to just viewing/filtering rights and define row-level security to ensure they only see data according to your governance policies. Furthermore, we have capabilities to help both the owner and designer understand when a shared dashboard has been updated and how to apply local changes to apply across the entire deployment.

You can have a second Admin account to manage reports but you have to transfer ownership of the dashboard.