2 nuts on valve stem

[petdav]

Is there a consensus on where to install the 2 nuts that come on the inner tubes valve stem?

I have just spooned on new Heidenau and tube and have always placed the concave washer on the valve stem inside the rim, one locknut outside the rim partway up the valve stem and used the second locknut to butt up to the valve cap to serve as a locknut.

Local shop says leave one nut inside rim to secure the concave washer when installing the tube and valve [ makes it much easier! ] - but I'm not buying it, doesn't seem right to have this piece inside in this position.

I can't find anything on any tire manufactures' site - probably some urban myth at work here.