It looks like the hydrogen of the tyrosine is pointing at the hydrogen of one of the serines, so that the serine is "bonding" to the tyrosine as both an acceptor and donor to count for two bonds. This should not score so well; I'll dig into it a little more. Thanks for pointing it out!

Just to follow up, apparently this is a known issue in Rosetta, but happens rarely enough that it's usually not a problem.

To be clear, this is physically unrealistic—a hydrogen bond could never form with two hydrogens pointing at each other like this. But when a hydroxyl serves as an H-bond acceptor, Rosetta does not consider the position of its hydrogen (that is, the hydrogen that is not participating in the H-bond).

There is a fix for this in development, but it will be some time before that makes it into Foldit. In the meantime, we'd appreciate if you can keep an eye out for this problem, and share with us whenever you encounter it! If Foldit players encounter this problem frequently, we want to know about it!