If you had read his first posting you would have seen that he wants to
remove the single connector on one end of the cable and split the wiring so
he would have two connectors to run to two systems.
I would guess that doing this could possibly screw up the impedence match of
the cabling, especially if the two systems happened to be on at the same
time, and probably destroy his incoming wiring and/or signal.
Actually he said "split one ethernet cable to 2 connectors", and I was trying to
convince him to use a router and do it the easy way. I don't know about the
impedance issue, but untwisting the paired wires in an Ethernet cable is not
something I'd recommend. And what would he have on the other end?
This idea of making one 4 pair cable serve as a pair of 2 pair cables, simply
because you have only 1 cable in place, and 2 computers, comes up periodically.
It's a lot easier to use a hub or router than to worry about it.
Terminating a 4 pair cable with an 8 pin plug is hard enough; splitting it into
a pair of 4 pin plugs (8 pin plugs with 4 used), and getting the sequencing and
placement right, without untwisting one pair too much, would be an exercise in
futility. Do it the easy way and buy a hub or router.