Steps to reproduce:

1. Open the attached package 
2. Open VFX
3. Connect 'Spawn Event' GPU Event to 'Initialize Particle Strip' Init context

Actual results: Error is thrown, vfx stops compiling

Expected results: Disconnect connection from previous system if it connected to a new valid one

Reproducible with versions: 6000.4.0a1

Not reproducible with versions: 

Can’t test with versions: 

Tested on (OS): macOS

Notes:

• tested on trunk only
• Unity cannot compile the VisualEffectAsset at path "Assets/Repro-Context-Connections/New VFX.vfx" because of the following exception:

System.InvalidOperationException: Unexpected multiple GPU Event
  at UnityEditor.VFX.VFXGraphCompiledData+<ComputeEventListFromSlot>d__33.MoveNext () [0x0007b] in /Users/vita.skruibyte/Documents/unity/packages/com.unity.visualeffectgraph/Editor/Compiler/VFXGraphCompiledData.cs:1083