Even Johnson and Krumholtz acknowledge they're lookalikes.
I went to their Twitter pages out of curiosity to see if they ever mentioned one another. Recently (1 January), Krumholtz posted "Happy New Year ladies. I'm happily married. Don't cry, @markjakejohnson is still available. I know. He's a downgrade." (Note: Johnson's Wikipedia page claims otherwise, and lists Erin Payne as his wife.)
Back on 30 November, Johnson wrote, "@DaveKrumholtz if nothing else, lets shoot a short. I've wanted to play Luigi for a lot of years. All sad in drunken." Before this, he wrote, "@DaveKrumholtz I gotta say, and I mean this objectively, you're a handsome man, David Krumholtz. A very handsome man."
So that's that. I suppose I win the Lame Celebrity Stalker Award for the day. I also discovered, thanks to Twitter, that Krumholtz has thyroid cancer. That sucks.