When the Solarwinds backup is failing with the error “UNIQUE constraint failed: Node.NodeId, Node.SessionId. Error code: 19:2067 (constraint failed)” while trying to backup the location “D:\\oracle\\Temp” this is because the files are being locked while trying to run the job. To resolve this error, please exclude this folder by using these instructions:
Launch the Backup Manager client on the  specific server by going to the browser and entering http://localhost:5000.
Click on the Backup tab.
On the Files and Folders section, click on Edit.
Browse from there to the specific location you're looking for, in this case the D:\\ORA\ emp folder and uncheck the box to exclude it.
Then start a manual backup.