Z-Fighting on mesh with two materials on old Android devices

So I've been working on a mobile port of my game, and I've run into a weird issue. I'm using Unity 2018.2.20f1. On my Google Pixel, this issue doesn't occur, however on my Moto G (Android 5.1) and my Galaxy Tab A (Android 7.1.1) any meshes with more than one material applied experience z-fighting. For context, I'm using a darkened transparent material over the normal texture on quads in order to make them look darker. For now I'll work around it by just making separate darker versions of the normal materials (To be honest, I'm not sure why I didn't do this in the first place...), however in the future I plan on using multiple materials per-quad more extensively (Placing pictures over normal wall textures, for example) and I don't want this to be an issue. Anyone know how to stop the z-fighting? Thanks in advance for any help.