Raise only when different included blocks are defined

Perhaps, raise of error when **same** module gets loaded twice isn't best choice

This happens when module files are loaded first time (e.g. while app reloading) and further required by hand (because some lib don't expect such preloading) - e.g. see ctran/annotate_models#181 for
```
Unable to annotate concerns/promotional.rb:
Cannot define multiple 'included' blocks for a Concern
```

See #10652 and #10650 for initial idea.
Also checked, that Proc#source_location works on jruby & rbx, too
My personal opinion is that it should be considered valid to redefine the included block as long as there's only one.  The error condition the original patch was trying to catch was additional included blocks hiding the behaviour of others.

I would prefer to see a patch where redefining an existing included block from the same `source_location` is considered valid.