File url bug?

Shopify Partner
14 0 3

I have two stores for which I uploaded the same files in the Setting - Files area.  When I uploaded the files in the second store a random number was added after the file name.

First store:  onyx_50x.png

Second store:  onyx_50x_6e39aa53-191c-4043-a815-3e08be2bb822.png

Prior to this I had only seen this behavior when adding a file to the same store with the same file name.

When I used the liquid code

{{ 'onyx_50.png' | file_url }}

from the theme in the Second store because I did not notice at first that the file names were changed, Shopify returned the url associated with the file in the First store for which the second store does not have rights to access.  Given that the file locations on the cdn appear to be store specific I believe this behavior must be unintended behavior. 

I am not sure where to report this problem since the Guru's on the chat support and pretty clueless when it comes to anything but the basics.  Hopefully this is the right place.