I just ran into the same issue... as soon as you check the 'repeat while button is pressed' for an rs232 command, it's sent twice when you press the remote button even briefly, regarless of the ramp start value. I emailed Mike at surfremote about it, but I suspect a bug in the software.

Btw, the number of times the trigger command is sent from the remote can be changed on the MX-900, but shouldn't. All macro triggers are sent 3 times, but for reliability purposes only - it doesn't have anything to do with how many times the macro will be executed by the MSC-400.