The way SQL Server 2012 Express works is by registering
these App_Data databases by name across your entire machine and the
names are not allowed to be duplicated. So, if you have 2 copies of
PlanetWrox in two different directories, you are almost sure to run
into this type of problem? Could be the source of some of my problems that I have been having with SQL Server 2012 lately?

It depends on how you register them. If you attach them, names need to be unique indeed. If you attach them on the fly (using AttachDbFileName) then the name of the database will be the full physical path which is then unique.

Imar

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Imar Spaanjaars
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Author of Beginning ASP.NET 4.5 : in C# and VB, Beginning ASP.NET Web Pages with WebMatrix
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