Yes, it would be bad. We ate only the new ones.
Since you are Catholic [guessing here], you may notice the priest usually eats the leftover wafers for this reason. I have never seen any consecrated wafers left over.
Often priests or deacons (or other designated people) need to take Holy Communion to people who are homebound or in nursing homes or hospices. When I was very sick in the ICU, I very deeply longed to receive Our Lord and I was so grateful when my pastor Fr. Pete brought me Holy Communion.
So that's why they keep the Blessed Sacrament in the tabernacle, to be available to take to the sick and dying. The candle always kept lit next to the tabernacle indicates to adorers that the consecrated Body of the Lord is there.
I thought they were supposed to burn them and put the ashes down the sacrarium.