Ubuntu 13.10 AMD64 in Live Distro Bitcoin QT 0.8.6 Linux download
Start Bitcoin QT with
$ ./bin/64/bitcoin-qt -datadir=data
Open console window
$ importprivkey "xxxxxxxxx" "Label"
The adress shows up in Adress tab
$ importprivkey (same arguments)
Error .-4
The adress moves from Adress tab to Recieve tab
Behavior repeated consistently in the same environment.