BAR-K IS are good mid range without having to vet like riflemen, while double Bren Raid section are better than LMG lifmen at long range for 20 munition more.
The max range DPS difference for double Bren Raid Section vs M1919 + BAR Riflemen is negligible (18,9 vs 17,9) while being significantly worse at close to mid range in case they get overrun. In other words, it wouldn't be an issue. And I highly doubt anyone would use it anyway, because double Bren IS would be way better at mid to far range and the difference between the Lee Enfields at close range becomes negligible too, given how those models are the first to drop.
1 Bren and 1 Vickers combos might work, copying M1919 + BAR on Riflemen, but it'd be slightly worse. So it won't be an issue.