Padlocks always come with two keys. Make two sets of keys, and hang them in separate (ice based) key release mechanisms on the ceiling. Always use both sets of keys! The release mechanism based on ice is extremely reliable, the keys are simply guaranteed to come down, I have never seen a failure, but still other things can go wrong. For this reason, you must always use two sets of keys.
The risk of damaging keys is much smaller if you know in advance which key belongs to which lock. Always the keys in a fixed order, and always use the same lock on the same place. Mark the locks and the keys with marker pens.
Padlocks are very reliable, and I never had problems opening one, but one never knows. If a lock appears to get old, and difficult to open, then replace it. If you connect yourself to something fixed, then make sure that there are two locks (or a lock and a screwlink) in this chain as well, and that opening one of them is sufficient to get free.