PB 2019 R2 is same major version as PB 2019. They therefore by default install into same folders and use same filenames since filename contains major release, not minor release. This is "business as usual" for PB installations as far back as I can remember.
Likewise for PB 2017 R3 installed on top of PB 2017 R2 which installed on top of PB 2017 GA.
Windows 10 Sandbox loses all content when you close it (at least I never figured how to keep sandbox content) - so it is only viable for short-time experiments like install browser plug-in in a "safe" way.