BUG: Option-Drag does not work between spreads
It is possible to copy objects using Alt+Drag command. It works if you work on a single page or single spread.
Unfortunately it is not possible to Alt+Drag objects from one spread to another spread. This bug was introduced many years ago and it is still present in Adobe InDesign CC.
Please make the Option-Drag of object consistent and let users copy objects from one spread to another one.