2 Versions of FortiClients on 1 PC

Hi

Can someone help me?

I prefer to work with the old version of FortiVPN (4.0.2303). But sometimes it cant connect to newer versions of fortigates.

So the question is - How can i install the new vertion of forticlient, when the old vertion is still instaled on my PC, so i can use the new one, when the old one cant connect.

P.S.

I do not need to use them both at the same time.

All i need its installed both of them on one PC at the same time.