Yes, he understands. Once the concept of dopplegangers is an every day concept it's easy to understand why someone might be distraught about finding one of someone they know, love, or even hate.

"Jesse Quick, actually, is a speedster on Earth 2 as I understand. Johnny Quick not quite familiar with. As for Max Mercury, I don't think I've ever heard of him." Odd, that this world has so many absentee heroes. He wonders why as they enter the museum.