Repro steps:

1. Reload the all_interactions exploration and go to /explore/16/
2. Resize your browser window to be "narrow" (<760 px)
3. Play the exploration until the MathExpressionInput card
4. Submit the correct answer for the MathExpressionInput
5. The ngRepeat: dupes error appears in the console, for the variable hintIndexes.

The error does not appear to affect the learner experience.