[Lua] [Question] Why is my loop printing twice?

I've rewritten and simplified my simple program for an hour now, but this problem still persists. I'm using a redstone event and checking the back redstone state to change the front redstone state and print the result. I know it must be obvious, but I can't see it.

term.clear()
term.setCursorPos(1,1)
event = 0
param1 = 0
while param1 ~= "q" do
  event, param1 = os.pullEvent()
  if event == "redstone" and redstone.getInput("back") == true then
    redstone.setOutput("front", true)
    print ("Front is now on.")
  elseif event == "redstone" and redstone.getInput("back") == false then
    redstone.setOutput("front", false)
    print ("Front is now off.")
  end
end

The output print is doubled for either case.

"redstone" events are generated when redstone next to the computer changes. That means that when you change an output (turn on or off) it will also generate an event.

So the first event is changing the redstone state in the back, and then when the front changes, the event changes again, nearly instantly? Didn't think about that. Thanks!