When you copy and paste, or use the arrows to drag, the new position is sent by your computer to the sim, but your computer updates the position on your screen immediately. The fact you use the C and P buttons to copy and paste positions as opposed to hand-typing, or using the axis arrows, does not matter.
So, if a communications error occurs, the sim won't see the update-position message. A short while later, your computer gets a position-update FROM the sim. It does not match; so your computer moves the object to THAT position .. usually right back where it started from.
The source of the error is usually at one end or the other, and not somewhere in between. Problems between your home network and the simulator are wide-spread, effecting far more than just you and just the sim. You can't fix them. At best you can call your ISP or Linden Labs and hope its their problem, or they'll kick the problem down the line.
You always have the ability to reboot your computer and routers (or bridges, or modems), and that often fixes it.
As a sim owner, you have the ability to reboot the sim. Restarting a sim moves it to another physical computer, changing network cards, cables, and routers over at a Linden Labs site. Often that, too, fixes the problem; but is only available to those with Estate rights for the simulator.
KittyCatS complicate matters with their fall-asleep-and-jump-home behavior. This effect occurs no matter what prim-mode, pose, or other options you set on the cat. Manually editing the cat's position, however you do it, does NOT override this behavior.
So, if the object which just rubber-banded is a KittyCat, check its status. If the cat is asleep, with very low energy, it's probable the cat simply fell asleep on you and automatically jumped home.
The only way to stop this behavior is to click on the cat and set a new Home position after the move. Even then, there is a short window between the move and the setting of Home and cats can still fall asleep in that window. But, heck, they're cats, they have their own purposes, and our wishes rarely enter into their consideration
So, if you're on two different computers and networks (different continents often, but not always, indicates so), and you're both seeing the problem, either it's normal cat behavior, which setting a new Home position will stop, or it's the sim having problems.