Do you mean you have a SERIES resistor that is forcing a different net name at each end?
It seems like a parallel resistor across the two nets of the pair would still leave you two nets to define as "+" and "-"
you can not define 2 nets that are parts of one electrical nen in CES as diff pair
what i needis to seperete the 2 nets
To disconnect the two nets, you have to find the resistor as component in CES and untogle the series attribute. This will disconnect the electrical net into two nets.
Hope this helps
There is also an analog switch in the Constraint Manager that makes Electrical Nets in to Physical Net names.
If you get a message that it thinks it is a power net and it does not make it go to the analog physical nets you will want to look a the following TechNote:
That should help explain what is happening.