Yes—on Canon cameras with built-in Wi‑Fi, a connection setting/profile is typically tied to one specific device, likely by storing that device’s ID. So one saved Wi‑Fi setup usually equals one phone or tablet.

That matches the behavior you’re seeing: once one iPhone is registered to that profile, another phone may join the Wi‑Fi network but Canon Camera Connect still won’t complete the camera connection.

The usual fix is to create separate connection settings for each device. For example, you might save one profile for your phone and another for your wife’s phone, then select the appropriate profile on the camera before opening Canon Camera Connect on that device.

If you overwrite or erase a profile to register the other phone, the first phone may stop working until it is set up again.

So the issue is likely not the app itself, but that each camera Wi‑Fi profile is effectively single-device.