Don Short, agony uncle, answers your questions.
I AM increasingly concerned by an ongoing dispute between two colleagues.
The root of it is unclear but the conflict is affecting staffroom morale.
Our line manager appears to be trying to ignore the issue.
YOUR manager needs to be made aware of the situation - he might not know what is going on. Given the amount of paperwork the average line manager has to do, you can't blame him for not having an eye on the "shop floor".
Either tell him, or confront the issue yourself and be blunt.