It could be they were in the process of relocating, but didn’t want to committ in a new city until they had a feel for it, renting the house in the old city while you rent an apartment in the new city until you decide on where you want to live is a very economical way to handle such a relocation, then you can be pickier about the new house purchase and you have more flexibility in buyers for the old house if you don’t have to sell the old house before you can buy the new one