Idealy you would do the workout all at once, and then spread out your cardio if you enjoy going more than once a day.
The problem with doing the scenario you describe is that depending on the intensity of the workout in the morning, you may be over doing it at night before your body has a chance to repair. This is especially true if your second workout is heavily using the muscles you already damaged earlier in the day. While your muscles may have recovered enough to 'do' the exercises, you might end up over-working them to the point of ineffectiveness.
However if your schedule only leaves you with a few days a week to work out and you want to cover more specific workouts, you can try to pair up antagonist/unused muscle groups in the morning/night. For instance you could do a Back workout in the morning, and instead of doing the common pairing of Back and Biceps (I don't know about you, but my Biceps are quite well used after a Back workout!), you could do Triceps.
If you want to get even more specific in your workouts you could pair true antagonist muscle groups (using their full names) into splitting up workouts into morning and night:
- Pectorals/latissimus dorsi (pecs and lats)
- Anterior deltoids/posterior deltoids (front and back shoulder)
- Trapezius/deltoids (traps and delts)
- Abdominals/spinal erectors (abs and lower-back : caution here, do abs first!)
- Left and right external obliques (sides)
- Quadriceps/hamstrings (quads and hams)
- Forearm flexors/extensors