I want to make an event reciever DLL for both SP2010 and SP2013. currently I have two separate projects one for each as each one is targeting different framework due to the fact that each of them is built using different .NET framework. can I use one project/solution to produce these two different DLLs?
Use conditional compilation in visual studio to switch between dlls of target framework.
Refer below links for help:
Conditional Compilation and Framework Targets
Conditionally changing target framework version
visual studio 2010 compiler conditions based on target framework