multiple computers on the same set of cables

I have a problem with a password protected door I'm building. It is a doubled layered piston door with an output of 5 different colors and I got everything to work from one side of the door. Basically the door opens as I desire when I enter the password from the outside and closes automatically as I desire.

What I want is another computer on the inside of the door basically doing the same thing, but I can't get that to work. As the newbie I am I thought all I had to do was to connect the computer on the inside to the same rednet cables, copy the same program and it would work. I quickly found out that it didn't work like that and after a lot of trial and error I still haven't found a solution. So now I'm asking you guys, is there a simple solution to this or do I have so sacrifice a unicorn horn dipped in a virgins blood at midnight when all of the planets align?

Split into new topic.

Please post your current code and any error messages you receive when running it.

Assuming the door closes when a signal is applied, use a hard invert (such as a redstone torch) after the computers and before the door. Otherwise, you'd need to unlock both computers at the same time.

The way that I would do it… Is you have 3 computers with rednet / wireless modems… Then have one computer connected to the door that is the lock computer, the other two computers basically send a signal to the door computer to tell it to open.

That way you can send a signal from either computer to open the door.