Do Muslims have more than one wife?

Yes, but in exceptional cases. To have more than one wife is subject to strict conditions. The first of which is to have acceptance of former wife (or wives) and second is to treat them equally without any discrimination. This is allowed in exceptional cases. For example if your wife is life sick and can't practice sex with you or if she can't children for. Despite these examples the overwhelming majority of Muslim men prefer to continue with one wife.