Yes,you could certainly restore them.
To restore PuppetDB from one backup file and restore configuration, certificates, and code from another backup file:
puppet-backup restore /mybackups/pe_backup_03032018.tgz --scope=puppetdb
puppet-backup restore /mybackups/pe_backup_04042018.tgz --scope=config,certs,code
This will restore all your backed up data.