VPN

I would like to know if it is possible to bridge two VPN endpoints in the same subnet.  I realize there would be a big concern for IP conflicts.  In our case, we are using static IP addresses so that's not an issue.  For a training exercise, we are going to pack up half of City Hall and move it to a remote location for a disaster preparedness training exercise.  The servers that we are connecting to at City Hall will be looking for these client machines on the same (internal) IP addresses, even though they are at another location. 

So I ask you; is it possible to bridge all traffic between two VPN endpoints?

No.

Duplicate IP's would be amongst the least of your concerns. Forwarding broadcasts and other junk that you otherwise wouldn't could cause serious performance problems depending on the size of the network. Besides that, I'm not aware of any site to site VPN that will forward L2 and up. See OpenVPN in pfsense, that may be possible with it.

You should avoid hard coding IP's so if you have to move to another site you don't have to maintain the same addresses. Though in a real disaster situation, your primary network would probably be destroyed or at least completely unusable, so it wouldn't require maintaining the same subnet in two locations.