Ysing Crtl+C to duplicate instead of clone

As far as I know it always duplicates if you do it on the same frame. It'll make a clone if you do across frames (or applications).

UltraHammer - Interesting, but it always duplicates for me.
What kind of object is "wall" in your example? eg Active, Backdrop, etc. And where are you selecting the object before you use Ctrl-C to copy? e.g. in the frame, in the Object list, in the Workspace Toolbar name, etc.
The only way I can get a Clone is to copy and paste it to another frame, change the objects properties and copy and paste back to original frame (since the objects are different, it makes a Clone rather than a Duplicate)

I've also had it do one or the other, at various times. But it has been impossible to reproduce (for me at least), so I haven't submitted a bug about it. UltraHammer, if you could maybe record a video with the bug in action and supply a scene file with the problem, that might help solve the issue. I would love to see this issue fixed.

Are you just copying and pasting, or are you copying and then modifying properties before pasting? It seems to me the only time this should occur is when the pasted object is not identical to any on the frame.

It happens to sometimes as well, and I noticied it happends when you have behaviors or qualifiers.

My workaround is to select the object from the Workspace toolbar and drags it to the Frame.

Never happened to me even once. I usually don't copy objects with Ctrl+C and V though, Ctrl+Drag is often quicker.