Downloading DuplexDr 1.5 from the developer's website was possible when we last checked. We cannot confirm if there is a free download of this software available.
According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software. The actual developer of the program is Labtam. The program lies within System Utilities, more precisely Device Assistants. The most popular version of the tool is 1.5.
From the developer:
With DuplexDr, you can create a pair of virtual serial ports (VSP pair) "virtually connected to each other" in your system. A virtual serial port appears to application software as a "standard" MS Window's communications port (virtually identical to an RS-232 port). Data may be written to VSP by applications, and data may be read from VSP as though it were a standard COM port. Entering VSP pairs, you can create and use "a VSP pairs pool".
You may want to check out more software, such as COMMUNICATE!, GX30 USB-Handset Manager or Novell® ODBC Driver For eDirectory, which might be similar to DuplexDr.