@MotherDucker
Irrational, murderous anger when two 'versions' (for lack of a better word) of a time traveler exist in the same timestream. They suddenly have the inescapable desire to find and destroy that extra soul.

Note that this could be the entire plot of a movie. The pitch:

Gerald invents a time machine, to re-live meeting his first love. But when he arrives in the past, both he and his other self go mad.

Title: "There Can Be Only One"