The Group and Symbol Toolboxes include a button to move selected objects to another page.
Note - this is much quicker than cut and paste and also better, because Cut then Paste will cause a Removed and then an Added record in the list of Symbol Changes when doing a compare, whereas when moving objects this way a compare shows the change as a page number changed.
If you have a model containing a lot of data, moving objects to antoher diagram it destroys all instances that are related to the object.
(if you have a recent backup and good RealTags the lost data can be reimported using the Object instance data form)
cutting and pasting an object on the same diagram is even worse, as it destroys all instances that are related to the object.
Do copy and paste to create new object of course.