One thing is for sure(what i think atleast), Hudson/Nec didnt see it as an entirely different machine to replace the regular pc engine over night, it could play the standard pce games, you could hook it up to a scd addon or a cd rom2 with an adapter and so on, they didnt stop developing games for the older models and most importantly, what was it called....pc engine...core grafx pc engine.....core grafx 2 pc engine.....shuttlegrafx pc engine ....... supergrafx pc engine, it says it on the console and box, PC ENGINE.
If there were more games made for it, i believe they would have phased the regular pce out and gave the Duo the ability to play SG games.