Cannot make two connections with same IP to DME/NAT

[jtjanecek]

Issue introduced here: b2c5e84
When connecting with two PCSX2 emulators using the same IP, the second one to join will crash when joining a game

[jtjanecek]

Issue here:
b2c5e84#diff-01cc212ea73cfc38fee0b0a3d826854820990ec9d7ab2a9dc5ce8c613ef3ffb0L45