It has always annoyed me how BA doesn't list the true bag allowance even when BAEC details are registered. I have just checked 2 separate shorthaul bookings, one says 1x23KG the other 2x23KG.
AFAIK, Gold gets an additional checked bag for free. That's how I've always reasoned for having 3 bags when going doing longhaul on J anyway. In your case of shorthaul Y, 1+1=2.
My largest checked bag is usually 26-28KG and I've never had issues with weight apart from the one time when I had to rebalance a case which was over 32KG, I was told above 32KG isn't allowed for Health and Safety of bagloaders. This is almost always dropping bags at Gold/F desks on longhaul flights where the person at desk is typically better trained and more lenient.