To answer this & other similar questions...
Once a voucher has been added to a database it cannot be moved to be used elsewhere as a stand-alone pc.
If a terminal (A 2nd pc on your network) has crashed, you can simply use any other pc, install 4POS as a terminal & then either change the pc name in 4POSBackoffice or rename the new pc to the original name...
Obviously all sharing rules apply.