In normal operation your Little LogBook can be “De-Registered” and “Reregistered” to as many vehicles as you like, for example, when you buy a new car.
Little LogBook is not set up to re-register vehicles with matching registration details - vehicles previously registered on Little LogBook.
There is however a very simple solution that will address the issue.
Continue using your Little LogBook in the temporary vehicle. Download as usual to your existing vehicle’s database. When you get your vehicle back, simply extract a “Custom” report for the period in Excel. Update the vehicle details in the report to match the temporary vehicle. Print it out and save it. Use this report as your logbook.
To correct your trip readings in your existing vehicle’s database, select the trips using the temporary vehicle and delete the trips from your database. This will correct the odometer discrepancy.