Duke Dantalion might have been annoyed that you asked him a question that you clearly knew the answer to. What I did with my pennies is that when I first got them ready, I just used them for basic divination. At that point I would say something like “stupid question time,just trying to tune up the pennies.” and then I would ask a stupid question that I already knew the answer to. Almost like tuning a guitar. Did this the first time or two when using the pennies. After that, they were ready, because if you keep asking dumb questions, you will start getting dumb answers. Happened to me, so that’s how I know that a couple of times is enough.
The 2 heads and tails usually means yes, but it could also sometimes mean no. Usually an extra throw or two will get you more clarification, but I have also had that happen where the throws keep coming up 2&2 where it could mean one thing or another. After two extra throws, I don’t ask again. In my experience, this is the spirits making you think and sure enough, you will get your answer later and it will make sense.
Also, did you smudge your pennies before using? Gets rid of the bad shit and that way you can start fresh. After you really start using them, you will notice changes in the pennies.