two controllers - one phone

[goforit]

Is there any problem using the same cell phone for my Mini 2 controller and for another controller for my Air 2?

 

[Faster]

Is there any problem using the same cell phone for my Mini 2 controller and for another controller for my Air 2?

Not at all. You can use one phone with many controls you like. Almost all Fly app settings are stored in the aircraft/RC, not the phone

 

[cheddar-man]

Not at all, as has been said. The only time you need to do things is if you have one controller and two drones. Then you need to do the linking procedure. You don't actually need a phone or tablet to fly the drone, you'd just have to fly "manually, visually" and you wouldn't know what the camera was seeing.

 

[Yorkshire_Pud]

It is possible but there is one 'disadvantage' that I know of. If the drones use the same control App the various flight logs for the different drones are stored in common folders.
If you save your logs to computer and wish to separate/sort those downloaded logs by drone then things get slightly complicated.
If you wish to display the logs, sorted by drone, on the phone itself this is NOT an problem on the phone itself, the App can sort/separate the logs internally.

It might be a nice idea if DJI would add code to the App to make it possible to download logs for specific drones to the computer but I doubt that will happen.

You can also use multiple phones with one controller, not simultaneously. The disadvantage of that is that your logs are then spread over multiple phones so, unless you sync your logs by some means, the flight histories on each phone will only be partial histories of the drones concerned.
Syncing with DJI may wipe DAT flight logs, some people like to have DATs available (if they are readable).