After joining a server, it's impossible to join a server. The client spawns, but it doesn't do that server-side.
I mean, it doesn't send the packets requeired to spawn. Tested that with another 0.6.0 iPod touch 4 as a server, and the iPhone refused to correctly connect (disconnected after 20 sec) until I manually closed Minecraft.
Also tested with PocketMine-MP, so I can tell you that the ReadyPacket (0x84) is not sent in that case. The first time after restarting Minecraft works.