Teams of 8
In teams of 8, traditionally two teams of 4 will play the same set of boards against two other teams of 4.
Froma a scoring point of view, there is nothing that requires the two pairings (say Exeter A v Torquay A and Exeter B v Torquay B) to play the same boards.
Could they play different sets? Would that be meaningful, or is it essential that they play the same boards? If so, why?

Comments
There are 4 types of Team-of-8 scoring...CrossImps, Add then Imp, Imp then Add or Aggregate.
You could use different sets if it was 'Imps then Add' as the sets of boards are unconnected then. The other three require the same sets for any meaningful comparison.
Even with the 'Imps then Add', it would better to use the same sets as the boards may be more flighty in one set as against the other thus distorting the fairness.
Good point!
Why is that unfair? How does one team gain an advantage if set A is flightier than set B? I agree it seems "better" to all play the same, but I'm not sure that's actually the case.
You may be right....just my intuitive feel. If Set A has several iffy slams and Set B has routine part scores, then it may favour the better A squad. I can't prove it...just a 'feel'!
When the Garden Cities competition was played in a few counties (e.g. Hertfordshire, Cambridgeshire) in the 1980s, there were head-to-head matches - played privately as two teams of four in a home and away venue. Each match would shuffle and deal its own boards and the IMP results added at the end of the evening. This was fair but less interesting than having both sections playing the same boards.