The project file template(s) dont force VS to use a specific version of the LLBLGen classes.
For example
<Reference Include="SD.LLBLGen.Pro.ORMSupportClasses.NET20, Version=2.0.0.0, Culture=neutral, PublicKeyToken=ca73b74ba4e3ff27, processorArchitecture=MSIL">
<SpecificVersion>False</SpecificVersion>
<HintPath><[RuntimeLibraryHintPath]></HintPath>
</Reference>
Should be
<Reference Include="SD.LLBLGen.Pro.ORMSupportClasses.NET20, Version=2.0.0.0, Culture=neutral, PublicKeyToken=ca73b74ba4e3ff27, processorArchitecture=MSIL">
<SpecificVersion>True</SpecificVersion>
<HintPath><[RuntimeLibraryHintPath]></HintPath>
</Reference>
When you have v1 and v2 installed vs likes to default to using version 1 which is a pain.