When you're on a horse, clicking inventory button gives saddle equip sound every time you open the horses' inventory.

Steps to Reproduce (Saddle equip sound)

1. Tame a horse
2. Equip horse Saddle
3. Press inventory button.
4. You will get the saddle equipped sound.
5. Close your inventory.
6. Click inventory button again.
7. You will get the saddle equipped sound again!

EDIT

Steps to Reproduce (Armor equip sound)

1. Tame a new horse
2. Equip horse Armor
3. Press inventory button.
4. You will get the armor equipped sound.
5. Close your inventory.
6. Click inventory button again.
7. You will get the armor equipped sound again!