Proper climbing procedure states that partners should check each other's harnesses and the rope to make sure they're connected to the same rope, the knots tied

Proper climbing procedure states that partners should check each other's harnesses and the rope to make sure they're connected to the same rope, the knots tied properly, buckles are double-backed, etc. I had a similar incident many years ago where my partner only tied into one harness loop. Luckily it was in the gym and she wasn't on lead, but after that, I always make it a point to thoroughly check my partner's equipment.