Steps to reproduce:

1. Open attached project
2. In project view, select and reimport Packages/Code Coverage/lib/ReportGenerator/ReportGeneratorMerged.dll
3. Notice error in the console:
Assembly 'Packages/com.unity.testtools.codecoverage/lib/ReportGenerator/ReportGeneratorMerged.dll' will not be loaded due to errors:
ReportGeneratorMerged references strong named System.Text.Encoding.CodePages Assembly references: 4.0.1.0 Found in project: 4.1.1.0.
Assembly Version Validation can be disabled in Player Settings "Assembly Version Validation"
ReportGeneratorMerged references strong named System.Numerics.Vectors Assembly references: 4.1.4.0 Found in project: 4.1.3.0.
Assembly Version Validation can be disabled in Player Settings "Assembly Version Validation"

Workaround: Disable Assembly Version Validation in Player Settings

Reproduced with: 0.4.2-preview
Editor: 2020.2.2f1