On Sat, 15 Nov 2003 20:03:22 -0500, James Nipper wrote:

I doubt very much that the earphones with an inline switch actually turned
your laptop speakers on and off. That is almost always a function of the
mechanical workings of the earphone plug itself, which disables your
speakers when you push the plug in. If you had one of those earphone
plugs (plug only) and pushed it in to the laptop , it would turn the
speakers off, mechanically of course.

Could be wrong, but I think others will likely agree to the assessment.

Not with my laptop at least. IIRC most of them by checking the continuity,
whether a current can flow between the middle and outer parts of the
socket, rather than whether a plug is present.
For the OP, why not just use one of the one-socket-to-two splitters that
you can get from any electronics store?