Whose Horn is Longer?

Not familiar with the behaviours of this tiny Treehoppers, the one on the left have a broken 'horn'. I wonder if the males uses the Horns to 'head butt' when wooing for females or this is just a regular incident as after all, the horns are very thin/slender. The whole insect is less than 1 cm in size and the thickness of the horn is just 1 mm.