Here's what's actually happening ...
1 - There are two frob control boxes at the safe: one surrounding the items, and one surrounding the safe's lock.
2 - At spawn time, the second one is finding the bad purse and turning off its frobability. This is because the bad purse appears twice on the list of entities near the safe's lock. One of these instances has a good clipmodel size that doesn't touch the lock's frob box, and one has a much larger bad clipmodel size which does. The only other item inside the safe that appears twice is the other purse, but its bad clipmodel doesn't touch the safe's lock, so its frobability is left as is.
3 - At spawn time, when the safe's frob box activates (after the lock's frob box), it finds that the bad purse has had its frobability turned off, so it doesn't include it in the list of items that are affected by the frob box being activated. It turns off frobability of everything else in the safe, and puts those items on its list.
4 - When the safe is opened, the safe's frob box inspects its list and turns frobability on for all items it had turned off at spawn time. Since the bad purse isn't on the list, the bad purse remains unfrobable.
We saw this problem in A New Job, wrt the upper switch for the elevator and the frob box for the safe, which are on opposite sides of the same wall. We fixed that problem by making the switch unaffected by frob box changes, and I filed a bugtracker issue to figure out why the switch had an immense clipmodel at spawn time that was caught by the safe's frob box.
So the root cause appears to be that each spilled purse appears twice on the list of entities that get checked. One has a good clipmodel and other has a bad (large) clipmodel. One of the spilled purses gets caught by the lock frob box, and the other doesn't.
Since this problem involves a particular item (the spilled purse) and two frob boxes near each other, it is most probably not a widespread problem. Accountant 2 simply got bit by it.
I will look into this for 2.06. Prior to that, I can't think of any workaround. It might be that the spilled purse is not the only item that appears twice at spawn time.
The 'button inside a safe' not working is probably the same problem.