unfortunately Autocad doesn't work that way. Pasting objects of the same layer name from another drawing will not redefine the layer properties.
The way to do it that comes to my mind is to simply:
1) rename "Layer1" to for example "Layer2" in the second drawing,
2) paste into this drawing the object from the previous drawing (Autocad will create then "Layer1" again),
3) move all objects from "Layer2" to "Layer1".
4) Purge "Layer2"