Reproduction steps:
1. Open the attached project.
2. Go to "Assets > Plugins > NativeShare > NativeShare.iOS.plugin" and check it using file explorer.
- There are 2 .meta files
3. Build an iOS project.
4. Go to "Libraries > Plugins > NativeShare > NativeShare.iOS.plugin (RMB Click > Show Package Contents)" in the built Xcode project directory.

Actual behavior:
- You will see 4 files: .m, .h , .m.meta, .h.meta.

Expected behavior:
- Only 2 files are present: .m and .h.

Reproduced with:
- iOS Xcode build
- 2017.4.0f1, 2020.1.0a6

Notes:
- The core problem is that .meta files are generated int the Unity project plugin directory and then, all contents are copied into the build.
- Related to the case: 1178777
- It is possible, that in some way this issue also reproduces on other platforms.