Setup:

a.linq:
"a".Dump();

b.linq:
"b".Dump();

Delete all *.dll, *.pdb in plugins folder (for example, LINQPad Plugins\Framework 4.6), leave the MyExtensions.FW46.linq file for compilation;

Then run: lprun a.linq | lprun b.linq

This is the output:

c:\users\user\Documents\LINQPad Queries>lprun a.linq | lprun b.linq
IOException: The process cannot access the file 'C:\Users\User\Documents\LINQPad Plugins\Framework 4.6\MyExtensions.FW46.dll' because it is being used by another process.
at LINQPad.TaskExtensions.GetResult[T](Task`1 t)
at LINQPad.MyExtensionsManager.CheckForStaleExtensions()
at LINQPad.CmdLineAppHost.Run()
at LINQPad.Cmd.LPCmd.Run(String[] args)

b