"Remy, These problems can always be traced to Human Error". Yeah! The guy who wrote the firmware! The shutter release should do just that: operate the shutter!
Nikon learned that lesson on the D1x and D1h, on which the shutter release took a picture no matter what mode the camera was set to (except turned off). So in playback mode, or computer mode, the release still takes a picture. That was to correct a complaint on the original D1. Also on the D1, if you use single-frame mode with the monitor in review-mode, it takes forever for the camera to take a second shot. The camera does the processing to display the image, displays it, then stores to flash. It does not use the -big- buffer to take the shot when you press the release. Using "C"ontinuous mode gets you 4.5FPS, usually resulting in an unwanted second shot or too jerky movement on the release. I used the "Custom Menu Settings" to set the "C" mode to its slowest setting. That way I have 1 second to let up on the release, or press it multiple times as I want.
I suspect that the "programmer guy" for the RD-1 thought "Shutter pressed: if in review mode, stop processing current image and shutdown the monitor ELSE take picture. That way operator can use same button to terminate review mode with one press and take shot with second." I suspect firmware could be re-written to stop display processing of current image and and take the shot with one press of the shutter. Why not contact Epson and ask if the firmware can be modded?