Steps to reproduce:
1. Download and open the attached project
2. Build "ClientExample" scene for standalone
3. Open scene "ServerExample" in the editor
4. Enter Play mode
5. Open the standalone build
6. Press "ConnectToServerOne"
7. Press "ConnectToServerTwo"

Expected result: server switching is normally executed
Actual result: cannot switch to the second server

Reproduced on 5.3.7p2, 5.4.4f1 5.5.0f3, 5.5.0p3, 5.6.0b3*

FIXED 2017.2.0a3 trunk

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Notes:
*5.6.0b3 - partially fixed. Quick switching works, but after a few quick switches the client instance crashes
-If working, the text of Server Info and the text of Client State change to "Login" and "Connecting->Connected" repsctively
-Opening and connecting with 2 project instances in the editor works fine
-2 standalone builds(server and client) reproduce the issue
-Pressing "ClientDisconnect", which calls Client.Disconnect and then attempting to connect to the other server works fine