So I have 2 mac boot drives for the same Macbook pro: one is the internal HD and the other is a bootable external Thunderbolt 3 ssd, because I use 2 different version releases of a piece of software depending on the client. When I cloned the boot drive and then booted off the new boot drive, Dropbox made me re-sign in. It then did not recognize the yet another separate external drive I use for my dropbox files and made me reassign the drive and then spent hours re dowloading all the files. (huge video files). If this boot drive is an exact copy of my other one other than the drive name, I don't know why dropbox can't recognize it as the same user and not try to do this every time I use a different boot drive. The only solution I can find is to use dropbox web browser only for the 2nd boot drive. It would be really helpful to be able to use the same storage drive for my dropbox in app. I did contact customer care and Buster there suggested I put this in as a possible feature request.
If you’re using a different boot drive, then this would technically be a different login to your machine. The Dropbox desktop application recognizes each login as a separate device, which is why it redownloaded the files to your machine under that drive.
If the Dropbox folder is located on another external drive, then the files would redownload again, since different user logins to your computer can’t use the same Dropbox folder for permission reasons.
To prevent this, on that external drive you could try having one Dropbox folder for one login, and a completely separate Dropbox folder for the second login.