Definitely doesn't sound intentional. I don't see this issue here (Win 7.) Do you get this behavior whenever you paste anything, or just between rectangles that have been copy/pasted?
What happens if you alt-drag to copy, or use clone or duplicate?
Have you checked the Layers panel? You might want to make sure that the object is not locked. Also, is the object a "Rectangle" or a "Path"?
If it's a Rectangle, you should be able to adjust its dimensions with the Pointer tool. With the object selected, you can drag any of the control points (in blue).
However, if it's a Path, then the Pointer tool won't work to resize; it will only adjust the object's position. To resize, you'll need to use the Scale tool (Q), Free Transform (Command-T), or another transform command. Or you could use the Subselection tool to adjust the control points individually—but this will modify the vector shape instead of resizing it.
Also, if you find that Copy and Paste commands are causing some kind of bug, you might try Edit > Clone or Edit > Duplicate instead.
Hope this helps.