I got my O2 mobile broadband stick and i have this cable with it that has a pot to connect the stick and to ends that could go into laptops/pc’s. Does this mean i can use it on 2 laptops simultaneously? btw lost my manual.
If you place two on at once you will slow your connection right down. In theory mobile broadband was not designed to run two laptops at the same time.
Also don’t forget you will take only half the time to reach your cap.

It may mean that you can. But, normally the service is not very powerful so your connection could be very slow at times with both computers using it. If you have a Mac, then you can share the connection from USB through a FireWire cable (see your internet options pane of System Preferences), but it is quite complicated with other computers.
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If you place two on at once you will slow your connection right down. In theory mobile broadband was not designed to run two laptops at the same time.
Also don’t forget you will take only half the time to reach your cap.
References :
Experience
If you’re using windows, you can use the Internet Connection Wizard to share the connection to any amount of other computers using a network hub and some ethernet cables to each device.
References :