There is an example called Hawk-Dove in the book "A Course in Game Theory" by Osborne and Rubinstine.

Two animals are fighting over some prey. Each can behave like a dove or like a hawk. Each animals prefers to be hawkish if its opponent is dovish. The situation is shown as follows.

Dove Hawk

Dove 3,3 0,4

Hawk 4,0 1,1

The game has two Nash equilibria (Dove, Hawk) and (Hawk, Dove).

You could tell me the reason, couldn't you?