A second body can serve two different roles: backup and complement.

If reliability and speed on paid or important shoots matter most, an identical second body is very useful. You get the same controls, setup, and behavior, and you can keep both cameras configured the same. It also lets you carry two lenses at once and switch instantly without changing lenses.

If your shooting needs vary a lot, a different second body can make sense. For example, many photographers pair a full-frame body for portraits, landscapes, and low light with a crop body that is better suited to action or extra reach. That gives you more flexibility across subjects.

A common practical approach is to keep your previous camera when you upgrade. It may not match your main body, but it’s often a perfectly good backup and still very useful as a second body with another lens mounted.

So the choice depends on your priority:

• same body: best for backup, consistency, and professional redundancy
• different body: best for covering different shooting strengths
• older previous body: best value if you mainly want insurance and convenience