Installing Secure Client (5.x) AND Any Connect (4.x) on 1 computer

[marcobat]

I have a weird situation I need to connect to two sepaate VPN (not at the same time).
One of these requires Cisco Secure Client 5.x the second works with Any Connect 4.x.
I have Cisco Secure Client 5.x installed, if i try connecting to the VPN that uses Any Connect 4.x. i get an authentication and can't login.
(If I try, on a different machine, to connect to the second VPN using Any Connect 4.x i log in without any issue).
If i try installing Any Connect 4.x it tells me that a new version is already installed and it can't be installed. 
So it looks like I will have to install and uninstall them constantly (which is clearly a pain).
Obviously i could install one of the two in a virtual machine, but i would rather be able to work directly on my main machine while connected to either one of the VPNs.

Any better suggestion?
Any way to have the older VPN work with Cisco Secure Client 5.x? (i have no control over the VPN itself, it would need to be some configuration change on my machine).
Or any way of having both installed at the same time (with only one running at any given time).

Thanks.

[Aref Alsouqi]

Do you get any specific error?

[marcobat]

Yes the error is: "Login denied. You do not have permission to access this system".

I'm told by the IT people at the institution that it is because Secure Client 5.x is not supported. (and in fact if i use Any Connect 4.x it works like a charm). 

[Marvin Rhoads]

Indeed you can only have one version installed on a given OS instance. The admins at the one where it is not working may have created a DAP policy to block newer clients.

By default, a newer client can connect to headends with older software. I do it all the time and have done so for years since I connect to several dozen customer VPNs while I have always run the latest AnyConnect/Secure Client.

[marcobat]

Thank you Marvin,

I will try talking with the admins running the older version, I'm doubtful they will be willing to make changes for me, but I can try ...