I went to Dr. Chrome to get the Grounding Plating cyberwear mod. I already had Fireproof Coating - but after I bought the shock immunity mod, it only let's me slot one or the other. Was it always like this? I was pretty darn sure I was able to have both in previous playthroughs. Now it seems there's one of each and I can only fill all 3 slots if I get subdermal armor / one immunity / and optical camo.