What follows is a copy-paste of this Skype forum post. I’ve tested this on 10.8.2. Seems to work.
We do not officially support or recommend running two instances of Skype simultaneously on the one computer. However, it is possible to do this:
Make a copy of Skype:
- Open Finder.
- In the sidebar, click Macintosh HD > Applications.
- Click Skype to select it.
- Press Cmd+C, then Cmd+V to copy and paste Skype.
- Skype copy appears.
Change the bundle identifier in the Info.plist file:
- Right-click the copy of Skype and select Show Package Contents.
- Click the folder named Contents, then open the Info.plist file.
- In the Info.plist file, locate the bundle identifier setting, com.skype.skype and change it to com.yourname.skype (for example: com.john.skype).
- Go to File > Save, and then close the file.
Change the data path used by Skype for storing data files:
- Open Terminal (Go to Finder and in the Search field, enter Terminal).
- In the Terminal window, enter the command:
defaults write <new bundle identifier > DataPath <”path to a new data directory”>For example:
defaults write com.john.skype DataPath “~/Library/Application\ Support/Skype\ copy”
Note: after Microsoft had terminated support for older versions and forced everyone to update their Skype this step returns an error now:
2014-08-23 11:13:58.912 defaults[45773:707]
Rep argument is not a dictionary
Defaults have not been changed.
However, I just ignored it and started up Skype and it worked. I can still run two copies of Skype as before.
- Press Return.
You can rename Skype copy to anything you’d like it to be. For example, you could use Skype business instead. This comes in handy, because when placed on a dock a tooltip will display this Skype business name and make easy for you to distinguish which Skype dock icon represents what instance.