I don't think the naming is the primary challenge in handling duplicates.
It is because rclone like 99.99% of all programs is built on the core assumption that path and filename uniquely identifies a file. Think about a command like this:
fileHandle = openFile("hello.txt")
Most programmers would expect it to open a single file and return the corresponding fileHandle. It would require quite some reengineering in the core of rclone to make it treat fileHandle an array of fileHandles. The next questions after doing that is how to compare (when some backends don't support hashes etc.), how to list, etc. etc.
This GitHub issue illustrates how apparently simple and quick fixes like renaming in the backend suddenly opens for a lot of other questions and difficulties:
I am not saying it is impossible, just that it would require substantial sponsorship or development contribution.
It may be less demanding to make a dedicated Google to Google copy/migration tool from the ground.