Working with two WinToGo HDD

There is a fault in working with WinToGo HDD

the SSD WinToGo server may get confuse and reboot or hang by itself

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Anyway, I have now two WinToGo USB 2.0 HDD

so I thought of connecting to the nettop with  WinToGo SSD

First of all, here is the experiment results for few booting up session

1. Boot with a USB WinToGo will seem always got the USB boot up
no matter how to change in the Bios

2. With two USB WinToGo, I can choose and swop to boot from either
of the USB WinToGo 2.0 HDD

3. No matter inside the Bios, I disable USB HDD boot up or devices
(also only one USB HDD will appear - I think HitaChi does appear most)

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After the experiment, I removed both USB HDD
and boot into SSD HDD on windows 8.1

Then those strange phenomenon occur
the screen flip or hang
later it auto reboot few times

(Maybe the previous session, the USB HDD is running
so it still trigger the internal wintogo server to believe there is another session of
external wintogo is running)

at the end win 8 boot into repair screen

However, this time I continue to boot to Win8
(Then i plug in the USB HDD after bios session)

then boot into Windows 7
(hoping it does a disk repair by itself)

Finally go back boot into Win 8 with any USB HDD attached

So for my configurations
of using ECS nettops MotherBoard
So far that is the only way to use the external USB HDD
is to boot from just internal SSD
Then after Bios and/or Window 8 UEFI screen appear
then i connect the USB - very bad  but no choice at the moment