If you own a CD with it having a joint ownership(2 people) and the CD has beneficiaries. If one of the owners dies how does the CD work? Does the other owner become full owner of the CD or does the money in the CD go to the beneficiaries?

Depends on how ownership is worded. If its joint tenants with right of survivrship the joint tenant gets it. If its tenants in common, the beneficiares may be entitled to the deceased owner's share.

Can also be worded POD name or Payable on Death or ITF for In trust for.