Here's something interesting I discovered yesterday:
When BlueDuino is in Central Role, if you set scan duration to 10 seconds, and then scan for a beacon that is advertising once per second....
You would expect to get 10 scan results BUT in fact, you only get one result. This is because (I think) the CC2540 has a built-in function that prevents repeat results. This can possibly be turned off via the firmware of the CC2540, but I don't think we have access to that.
I am using version 2.1.5 of BlueDuino, so maybe this has changed in the newer versions. I would assume not.
Just thought it would be interesting to share this observation. I learned the hard way by setting the scan duration to 99 seconds and then going crazy trying to figure out why I was only getting one scan every 99 seconds when my goal was to get as many scans as possible. Me dumb.