This is only the 2nd time I have seen this, but it's a problem that needs fixing, in the meantime it would be best to avoid any puzzle with 2 equally valid solutions, when the puzzle can only accept 1, wrongly calling the other solution incorrect.
As already mentioned by others this particular puzzle can be modified to create only 1 correct answer.
Corrected by changing 2. ... Ke5 to Ke3
Please post a +1 to help fix this fault/ limitation/ restriction affecting Daily Puzzle & Tactics Trainer & if you like include a polite, positive, constructive message regarding any improvements that you would also like to see.
You can also include any examples if you wish
I've included examples that I've seen on the Daily Puzzle, where it just stops, instead of showing it's useful/ instructive continuation/ conclusion.
Tactics Trainer also suffers from this fault although any Tactics with more than 1 equally good solution are excluded or cut so short that the solver will not be able to see the useful/ instructive, continuation/ conclusion.
Example 1, from August 11th 2017:
From page 1 onwards of this Daily Puzzle:
https://www.chess.com/forum/view/daily-puzzles/8-11-2017-feminine-power you will see lots of people stating the problem that puzzle says 3. Qg5# is Incorrect, because the other correct 3. Qd4# was chosen instead.
The puzzle can only accept 1 of the 2 correct solution moves (both are mate in 3).
Try for yourself on the Daily Puzzle page:
https://www.chess.com/forum/view/daily-puzzles/8-11-2017-feminine-power
Or here:
Try 3. Qg5# which definitely is Checkmate, yet the puzzle will wrongly say Incorrect
Clearly 3. Qg5# is also an equally valid checkmate but the puzzle will say it's incorrect because the program can only accept 1 of the correct answers, 3. Qd4#.
Hopefully you now understand the problem (if you didn't already) that the program needs fixing/ updating/ improving.
Please post a +1 to help fix