If you want something like that, you will need a global variable to store the name of tileBG in Layout 1
var randomTile(String)
On Start Layout:
Set randomtile to choose("Colour06","Colour07","Colour08","Colour09","Colour10")
Create object randomTile on layer "COLOUR" at (-100, -100)
Then you can move to Layout 2 and create the randomTile only