Duplicate house key?

[Stug3]

Ok this is probably a simple question and I will have to hide my head in the sand but I cannot find the answer...
 How do I get an additonal house key for a renter?
 
 Thanks

[Pibemanden]

Buy a house key creator and place it inside your house and drop a key into it, then you pay 20gp and get a key in your inventory plus the one in the chest, it only works for the house it is placed in though