And I got interesting corrections from several people. They told me: “type /secondary as a “command line” in Skype.exe”. I had to search on internet how to do it (years I didn’t do that, this is DOS stuff!).
Why is this interesting anyway? Well, suppose your partner has a Skype account, you have one yourself, and your kids have one. Shit … only one computer in the living room, who will run his Skype account? Well, running several Skype instances solves the problem!
Step 1:
Locate your Skype.exe file in (usually) C:\Program Files\Skype\Phone
Right click it, move your mouse to “Send To” and choose “Desktop”:

Step 2:
Go back to your desktop. Right click the Skype icon. Click on properties (the last item on the bottom of the list).



From now on, even if you have already a Skype instance running, you can open as many other instances as you want, as long as you log in with another username. In the screenshot below you see 2 accounts running, one logged off.

This post is only applicable to Windows computers. I apologize for Linux and Apple users. And, it works only with the 4.0 Skype version.