Serial Splitter 

Use Serial Splitter to split serial ports at one side into multiple virtual and real serial ports at the other one, as well as join multiple serial ports into one. The unique feature of this version is many-to-many ports splitting/redirection.
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AlarIT Virtual Serial Driver (AVSD) 

AVSD is appointed for emulation of one, two or more (up to 200) serial streams. Hardware devices are not necessary. This product is based on Windows XP DDK and doesn't require using devices of other manufacturers.
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VSPD.net 

Network Virtual Serial Ports Driver is an advanced utility, the purpose of which is to emulate null-modem cable on computers located in a TCP/IP LAN or connected to the Internet by creating any number of pure virtual serial ports in your system.
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