How to reproduce:
1. Download the attached project "1171200.zip"
2. Open the command prompt and navigate to the Unity installation folder
3. Run the command "Unity.exe -runTests -testFilter NewTestScript;OldTestScript -batchmode -projectPath PathToTheProjectRootFolder" in the command prompt
4. Wait for the tests to finish
5. Investigate TestResults file in the project "1171200" root folder

Expected result: 2 total tests are run (see line 2 of the file)
Actual result: 3 total tests are run (see line 2 of the file)

Reproducible with Unity versions: 2018.4.5f1, 2019.1.12f1, 2019.2.0b10, 2019.3.0a11
Reproducible with package versions: 1.1.8 and below

Notes:
Until Unity version 2018.3.0f1 installing test Framework package would result in Console errors.
Console errors might occur when upgrading the project. If that is the case, the project will have to be opened without batchmode and packages reset to default.