Moving a file is duplicating it

[Fu Manchu]

What I have:
10.12.6
Two drives.
A media drive
A start up volume.



What is happening:
When I move a file on a thumb drive or on the start up volume on the mac, it moves it. Done.
When I am moving a file 'within' my media drive, it is duplicating the file.
When I search this, I can't find a straight forward reason why.

Any ideas?

 

[Wando64]

As far as i can see, the usual default behaviour is that it duplicates from one volume to another, but moves within the same volume. In any case you can change the behaviour by holding either the Option/Alt key (for duplicate) or the cmd key (for move).