Why is message sent and received at same time?

Erased and restored my phone 4S via iCloud backup in mid September as contacts were lost several times in same week. Because my own device backup missed so many contacts, so I restored my device with my husband's backup. We use same iCloud account.

The result, I got all my contacts back. However, a strange problem also turned up: whenever I sent a message to my husband, the same message message was sent and received at same time.

Why is it happened? How can it be resolved? Do I have to erase and restore with my own backup this time? What about missing contacts if I use my device backup? Many thanks here.