Reproduction steps:

1. Open "SG_CustomInclude.zip" project
2. Reimport "TestGraph" shader
3. Notice error

Expected Result: Having multiple Custom Function Nodes with multiple functions from the same source produce errors
Actual Result: You can use multiple Custom Function Nodes with multiple functions without errors

Reproduced with: 2019.2.0a9, 2019.1.0b8, 2018.3.10f1
Did not reproduce on: 2017.4.24f1 (No pacman)

Error:
Shader error in 'Shader Graphs/TestGraph': redefinition of 'globalA' at Assets/Shaders/CustomInclude.hlsl(1) (on d3d11)