What do you want to achieve?
I am attempting to wear this and this, both of which I own.
What is the issue?
Both the Roblox app and the website are only allowing me to equip one or the other. Profile
I’m not sure if this is some new change, but I have been allowed to equip both at the same time in the past (see my DevForum profile picture; It has both equipped as it has not updated yet).
To my knowledge it only shows if you’re on PC (or using the desktop view feature on a mobile device) and should be visible directly underneath your accessories.