Icons for resource packs and behavior packs will overwrite each other quite randomly. Experienced on iPhone 5, iPad mini 3, and HP laptop.
See attached screenshot.
A search was performed for this issue using the following keywords: "resource pack icon", "resource pack image", "resource pack picture" and "resource pack thumbnail". No relevant results were found.
I was going to report this but I think it's probably the same bug so I'll add it here.
When two resource packs are installed in the Global Resources list, the same icon is shown for both. These are converted PE texture packs (Faithful PE and CodeCrafted Custom PE). I reorganized the texture files and wrote pack_manifest.json files, giving each unique uuid's, names, and descriptions for both the add-on and the resource pack. I then built .zip files, renamed the extensions to .mcpack, and installed them by double-clicking.
I have checked that the pack_icon.png files in the com.mojang\resource_packs subfolders are correct and different.
The duplicate icon also appears in the resource packs list in world settings, whether or not one or both packs are activated for the world. The world folder itself has no resource_packs subfolder.
Deleting a subfolder from com.mojang\resource_packs will cause the remaining global resource pack's icon to be correct.