Kasun has answered the disputes about mal mitak. I think one of the parties that contributed to it really wanted to include that melody.
A nit:
As someone once said nobody is original no more. You could nit pick on any selected work most of the time. I don't think most of them have fraudulent intentions. Even maestro Kemadasa "plagiarized" kolmura kavi and some african folk music that were not presumably at his reach. That's the beauty of the music. If we murmur a tune now, that might have been sung by a Balangoda manawaya 25000 years ago.
About copyrights, some might have expired so in public domain or the original artists may not care. I think one reason that streaming services like Spotify are reluctant to come here is the copyright thing is/was not properly in place here and of course piracy.
