A database can have multiple databases that can use filestream. The only problem is that they cannot share the same data directory where the filestream container is located. Each database must have its own datadirectory that will have the filestream container in a subdirectory of that directory.
The setup should be like this:
F:data3filestreamcontainer1filestreamfiles
F:data2filestreamcontainer1filestreamfiles
F:data3filestreamcontainer1filestreamfiles
The directory presented above is a good example.
When you restore databases that are using file stream, like for example a memory optimized database then you will definitely get a restore message error with the popup.
When you encounter a restore error like this then it is best to create the database first in the instance and then restore over the already created database.