There is no way to turn off the Wire Auditing that was added to SI 5. This function was added so that the same wire was not accidentally used to connect two different components, thus causing anomalies on your wire schedule reports.
In the future, we may add the ability to "spit" wire ends so that you can make connections like w/ a siamese cable or for a component cable but for now the end of an SI 5 wire shape can only be connected to one I/O.
Another change to be aware of is that each end of the wire shape is now treated differently. See this post for details:
http://www.d-toolsblog.com/?p=300
What I have done in the past is to just draw a line to the other connection point to visually represent the connection on the drawing page. The drawback is that the reports only read the one connection made with the SI 5 wire shape.