I have figured out how you can still have 1.3.2 installed for revit 2016 after installing revit 2019, this is because for some reason revit 2019 blocks you from downgrading dynamo to a lower version than 1.3.3.
System Prepwork:
Uninstall revit 2019 and have the highest version of dynamo as 1.3.2 with all others uninstalled
Install procedure and changes to revit 2019 installer:
Within the revit 2019 install folders there is a copy of the dynamo installers within “x64\dyn” these are version 1.3.3. You need to replace these with the dynamo 2.0 version of the msi files. Then you can install revit 2019 and it will automatically install dynamo 2.0, without effecting dynamo 1.3.2.
Note: when i say dynamo i mean dynamocore and dynamorevit.