Does studying flashcards, both front to back and back to front, decrease retention opposed to only memorizing one way? From this spaced repetition type flashcard user manual one can,
"create cards that go in both directions (e.g., both “ookii”→“big” and “big”→“ookii”)."

In other words, would studying two flashcards (both with the same content but in reverse order, lessen the benefits of studying right at the periphery (i.e., spaced repetition)?



Here is a related question: Are spaced flashcards effective for learning?

Any comments with relevant studies is welcome--along with help. Feel free to edit or add to any idea to make the question less unclear.
No, it just makes the intervals suboptimal. Either bury the card if the opposite side came recently or change the card to the direction it will usually appear. (Sometimes it will be the description first.) The forgetting curve, memorizing right at the periphery, will still go back up: 


There is also the study done by Glenberg Smith &amp; Green about this...

Anki is programmed to deal with similar "sibling" cards
The algorithm will bury them--except when learning...


https://www.quora.com/topic/Spaced-Repetition
https://www.reddit.com/r/Anki/
https://anki.tenderapp.com/