I believe the deck building option is bugged if you spin and receive the same card twice in a row.
To clarify a little bit, this is the case (though it is not entirely certain whether this is a bug or a feature). It has nothing to do with spinning the same card twice in a
row, but it is based around it being the same oracle card. You cannot submit a new deck with the same card as your current deck, whether it's the next day or a month later.
I am unaware of any official statement as to whether this is a bug or a feature. It could be intended behavior in order to keep the arena varied and prevent the same deck from being resubmitted twice in a row. It could also just be a side effect of the way the back end determines what is considered a new deck (i.e. oracle card). If it
is unintended and undesired behavior, it could be fixed by just having the game store a "new arena deck" flag that is set when you spin the oracle. However, as this comes up almost never, it is not (to me) a high priority thing that needs fixed. The odds of it happening any given day are miniscule (well under 1%).