Yeah, the answers are above but in separate posts.
If you are locked into something like a spectrum, just rig a switch, and it will take a second to switch binds from one TX to the other.
If you are not locked in, go ELRS as @CarolineTyler said.
In openTX world, you can clone a TX/model. It copies over the bind data. If you have a multiprotocol module, this can even be done with DSMX. Not really the safest way to handle sharing a model because at some point, someone could fire up the other TX, and at that point, it's anyone's guess as to which TX will be in control.
I would prefer to bind it to the radio that should be in control.
My Spektrum IX12 will not copy the bind data if you transfer the model to a new radio now (it used to when I first got it, but an update came through a while back that stopped it). I thought at first it was a PITA to have to re-bind models, but now that I see how it could be a problem, maybe it’s actually a good thing…