This may happen if you still have the Bidirectional Support Enabled. To disable this and resolve the printing issues you may take the following steps:

1. Go to Start > Devices and Printer
2. Right click the printer > select printer properties > navigate to the ports tab
3. Uncheck enable bidirectional support
4. Apply and save

One you have made these changes, you should not be able to complete multiple test prints in Altru.