I am the American service technician for an italian company. All of the machines that i install get version 12 of teamviewer. But anything installed by the italians, have version 10 or older. i can not simply update those machines because the italians have machines in other countries that also have version 10 or older. So i need to be able to download both version 12 (or the newest) plus version 10 and have both of them on my computer at the same time. So that i will be able to support these older machines as well as other manufacturers' equipment.