I think Cyriack is talking only about rings/earrings.. If you have D.Ring & Sniper's Ring on, then try to use an /equipset with Astal Ring & D.Ring, it can fail to change either/both of the equipped rings. It's a tip to make sure that you keep your Left and Right organized when building sets.
Augments are a different can of worms, but the official workaround is to spread out identical gear (w/ diff augs) throughout your wardrobes/inventory. Just make sure you rebuild your /equipsets afterwards since they track which bag the gear is supposed to be in.