One of my cats got prescription urinary food. Second one can eat anything, and really shy.

I got shy cat a petlibro feeder for her dry and she is sacred of it , and eats prescription food which is in open access.

So, at this moment I am bit lost on how to feed both cats their food. Should I get another petlibro feeder so they forced to split? What if shy cat would never trust opening of the lid? What should I do for wet food? I am trying split them up, but again one is stealing food and second one is too shy to protect her food