John
Can I ask, when you say "checking your rifles regulation and grouping" do you mean when working up loads or just shooting the gun on target with factory ammo or reloads that have already been derived from pressure and 'on POI' spec.

When observing some of the videos posted the field use of a double can vary considerably to what maybe achieved on the range. Some shots taken on animals are just a single round, others a 1-2 and others a 1-2 reload 3-4 and even sometimes a 5-6 or a variation of these combinations (e.g. 1-2, 3, 4, 5-6 often with right barrel firing the 3rd and 4th and 5th shot after reloading the gun over a short period of time).

In other words I'm guessing that despite what might be practice on the range to cool between shots, in the field all this can go out the window and be meaningless in terms of 'patterning' of a double gun. Perhaps to get a better handle on the potential changes to POI with a double, combinations of shots as I have outlined above would be a better indicator for use in the field, if the POI indeed changes that much to make a difference for close in shooting?

Generally with a bolt gun I have found it is advantageous to shoot at least a mag full fairly quickly to duplicate possible field conditions as this will show up where bedding or floating the barrel is needed if the POI starts to wander or string. Unfortunately if a double does this there is probably not much that can be done about it other than just being aware and maybe compensating for a change in POI.