Do you want it to still be pick-up-able?
if not then can't you just make a new static object?
First, unpack the nif file of the shield you want to use from the meshes.bsa and place in the data/meshes folder (make sure you preserve the file structure eg meshes/armor/iron or how ever it is set up, not by my pc at the moment). Then in the ck, click on the "statics" branch in the object list, then right click in the list area and select "new". Then just select your duplicate nif as the model. Then give it a name and click ok
If you kept the default file structure then I don't think you'll have to redistribute the nif because everybody else's games will just look for it in the .bsa. The unpacking step is just for our end because (as far as I can tell) you cannot select a model from inside the bsa in the ck (I'm doubting myself now... Can someone put me out of my misery please by confirming/correcting the above

)