Ask HN: Does it EVER make sense for a startup to work on two products at once?

Would love to hear the HN community's feedback on this this...

My startup (based in Korea) currently has two products which have both had some early success with great partners (Evernote & Nike) and we're having a lot of trouble deciding which to focus on.

Does it ever make sense for a startup to work on two products at once? If not, then what kind of questions should we be asking to determine which one to focus on?

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Product #1

Mobile application. 3 language studying tools in 1 beautiful interface - A multi-language dictionary, a flashcard generator, and a vocabulary list. iOS paid app ($3.99 full price). Tens of thousands of downloads. Won an Evernote API hackathon in Korea which has led to a great working relationship.

Link: http://cookiewords.com/en/

Product #2

A social network for amateur athletes (team sports) - Organize games more easily with your friends, and see what sports and when/where all your other friends are playing. Used by Nike Korea as official mobile application of a nationwide summer youth soccer event.

Link: http://nikeinc.com/news/nike-cup-247-brings-mobile-innovation-to-the-pitch-in-korea