It seems there was a bug: keys were not removed from disk, so re-adding them failed. This should be fixed now - could you test again?
Ah, now it seems to work. Great! 
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Well, removing addresses from accounts is just not supported yet. It may cause inccorrect account balances, but not invalid total balances
Even getbalance for the account shows 0 after the keys are removed, even though getaccountaddress still knows it.Are you planning on adding that? (Not that I find it important, just curious what to expect
)Another question: is there a way to check the 'balance' of a single address/key?