I want to make this work: - 1 computer - 1 skype account - 2 headsets (for 2 people)
It's for making conference call with 2 computers but with 3 people (2 of them in the same computer under 1 skype account).
How I can do this?
You should get 2 audio splitters - one for the headphone slot and one for the mic slot.
Then connect both the headphone connectors to the splitter which is inserted in the headphone slot, and both the mic connectors to the splitter which is inserted in the mic slot.
This will allow you to have 2 headphone sets connected to your computer at the same time.
I use this for my current computer for skype so I know its possible.
This is what it looks like:
This model is better if the space between your headphone and mic port is small
Or this seems to be more flexible:
You can always do the call on the PC with a microphone and speakers. I often use my laptop's built in mic and speakers when joining a Skype conference with more than one person in the room.
rzlines' answer is, electrically, kind of weird. It may work, but I would guess it's because the headsets are identical and you're not talking over each other. The audio quality is almost certainly degraded, however. See this article on why using a Y-splitter backwards is bad.
The "right way" to do this would be to use a tiny little mixer to mix your microphone signals before going to the input of your sound card (or build the project described in the article referenced above).
However, what I would recommend in your situation is to simply split your headphone output and use a simple desktop microphone to pick up both of your voices. When you think about typical conference-calling systems in company boardrooms, they're usually just using an omnidirectional condenser in the middle of the table.