Shared folder with same name

It might be worth your time to learn how to handle the "ownership issues and stuff".

I do not have a definitive answer, but it is possible to attach an external hard drive to a Mac and to instruct the OS of that Mac to ignore all file permissions/privileges on that external hard drive. If those files and folders on that external hard drive are then shared over the network, (I do not know for certain) it may be possible that another user on another Mac across the network might also access those files without regard to the permissions assigned to them by default.

Try this:

In the Finder, mount the external drive and choose File: Get Info. In the Info window, at the bottom, click on the Lock button, authenticate, and check the box next to "Ignore ownership on this volume".

While we are examining this, here is how to give your coworker full privileges to access a shared folder or volume that is on your Mac or attached to it.

Under System Preferences: Sharing, enable File Sharing and add that specific volume to the Shared Folders list using the plus button under Shared Folders: For good measure, manually add your co-worker's name and password under Users: and give them Read & Write privileges.

Finally, there is a freeware graphical utility that you can use to change all file permissions on a file or folder without needing to use the command line or the Finder's Get Info windows. It is called BatChmod. However, using it can have unintended consequences if you do not have a good understanding of how Mac permissions work. Use this utility carefully and avoid using it on the contents of entire folders if you are uncertain as to what you are doing.

I use an alternative manager http://www.binarynights.com/ as a workaround.

If you copy folders there, Forklift will ask you if you want to merge them or replace. Replace option works how you would expect.

However, when you move folders, the replace is the only option.