I'm not sure if the sign belongs to the Allyndale or not, but isn't it on the property of the Cody Inn Apartments?

I think the sign is either to indicate "you can turn here to get to the Allyndale" or it might be a relic of the Cody Inn being a motel before it was apartments.

To further clarify:

The Cody Inn Apartments was the Cody Inn Motel during the late 1990s, and was the Tru-Vu-Motel going back into the 1980s and 1970s. 

So you might say the sign in this photo likely has nothing to do with the Allyndale Motel, since it's on the Cody Inn property ... however ... in the early 1990s, between its era as the Tru-Vu-Motel and Cody Inn Motel, the building was an annex of the Allyndale Motel. (This according to various Duluth city directories).

The sign is probably from the Tru-Vu-Motel era, but I'm just guessing.