The most easy way, with direct access to the machine is to copy the job folder from first jenkins to another one (you can exclude workspaces - workspace
folder), because the whole job configuration is stored in the xml file on the disk.
Then in the new jenkins just reload configuration
in the global settings (admin access is required) should be enough, if not, then you will need to restart Jenkins tool.
Another way can be to use plugins mentioned above this post.
edit:
- in case you can probably also exclude modules
folders