I am just showing you the major no-no's that I have learned about auditioning for theatre programs. Two completely different characters from two different plays and play genres. One classical and one modern piece is the norm. Make one a comedy and the other dramatic. One character may be a love-struck fool, the other a hacker nerd who let loose a devious computer virus.
Contrast is day and night.
Not shades of gray. But if all you can presently do is romantic, love-struck fools, at least contrast those fools by who they are and by each character's situation. Timing is everything Keeping your monologues under the time limit is the way to go. If you run over, you will be stopped. They will not let you continue past the time period stated.