If I were to run more than one VPN clients on my machine, simultaneously, what risks would be involved? 

E.g. are there technical conflicts, such that it wouldn't work right? 

Could there be address resolution conflicts? 

More scary, can traffic from one network cross over, via my machine, into the other network?  

Or can my traffic accidentally be misrouted to the wrong network? 

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If it matters, the VPN clients I'm running are Juniper Network Connect, and Cisco's AnyConnect (On fully patched and hardened Windows7). I don't know much about the remote endpoints...