It appears to be outside the tab control and therefore will appear on every tab. Try clicking & dragging it all the way off the layout, and then all the way back on so its borders are completely within the tab panel you want it to be in before releasing it. If you resize it and it pops off the side of the tab panel, you'll have the same problem.
Note how the selection handles extend past the borders of the tab control. This is what shows you that your layout text object is not within the tab control. The other test is to move the tab control a few pixels while in layout mode. If the layout text doesn't move with the tab control, you will have this problem.