Hi, i'm not sure if this is a bug or just normal... So i installed 2 tactical cornea implant on a colonist of mine. Then i got an advance bionic eye so i decided to install it in one eye. Now my colonist has 1 tactical cornea and 1 advance bionic. Then i stumbled upon a post saying that tactical cornea is better at hunting than advance bionic eye. When i decided to install tactical cornea again, there's no option available. I checked on my other colonist and they do have the option to install tactical cornea implant.
Maybe you should ask this at the mod which add tactical cornea, or RBSE topic for the adv. bionic eye.