Raspberry Pi Model A and Model B connected to LAN at the same time OK

So I moved on to test the WiFi adapter with the Raspberry Pi Model A.  What I did was the following.

1. Raspberry Pi Model B

*  Removed Logictec USB wireless keypad/mouse adapter from USB socket.
*  Removed Linksys WUSB54GC wireless adapter from USB socket.
*  Booted RPi B
*  Win 7 PuTTY logged in to RPiB to make sure it is still working with Ethernet cable connected.

2. Raspberry Pi Model A

*  Plugged in an USB hub to RPi A USB socket.
*  Did not connect 5V0 power to USB hub.
*  Copied the Debian image from RPi B's SD card to RPi A's SD card.
*  Booted RPi A.

3. Scanning devices in LAN

*  Use Win 7 Advanced IP scanner to check any device connected.

I thought I might need at least 30 minutes to change the parameter of some config files before the RPiA could connect to the LAN.  But very surprisingly, the IP scannerd found both the RPi B and RPi A connected to LAN!

.END