Win Win in negotiation is what experts recommend. That means, each party in the negotiation should be willing to yield or accept some level of compromise for the negotiations to reach a successful conclusion.
For example, the non-management staff union may make demands management considers a burden. If the union refuses to bulge and management also refuses to give in, there will be stalemate.
For the negotiations to proceed further, either party must be willing to give some concessions. At the end of it all, a position may be reached that is a win win situation because both parties benefit.
However, some people have questioned the use of the term win win to describe this situation. Since each party concede something to reach a win win position, proponents argue that it's actually a lose lose situation and not a win win situation.
Still others have argued that win win in negotiation situations should be referred to as BOTH GAIN because by conceding something, each party actually gain, since the concession results in stoppage of hostilities that would have made an already bad situation worse.
However you look at it, call it win win or lose lose or both gain, the message is clear: By being reasonable, by being yielding, by consenting to concede something in the interest of peace both parties win . . . one way or another.