Same name for two different PLCs?

What could possibly go wrong...

I'm at a new job, and I've been going through the PLC programs, getting online, making sure that I have a working path, saving updates as need, etc...

And I came across two different machines that have the same PLC name. The file name foe the project was different, but didn't indicate which was which.

So I tried the program out on the first PLC with that name and got the:

"the open project has offline changes that aren't in the controller" message. Trying it out on the second PLC allowed me to go online. Trying out the second program back on the first PLC gave me the "the open project has offline changes that aren't in the controller" message again.

Uploading and saving the file fixed this of course, but what the heck is going on?

Rest assured, I'll be giving these PLCs unique names in the near future...

The machine maker probably has a program it uses in all machines. I used to work on Minster stamping presses and every PLC had ladders for all varieties of their presses, they just enabled the ones that were appropriate.

I also work on some mylar laminators that apply a film to both sides of circuit boards, and not only are the SLC5/05's all named the same but they all have the same IP address (so they can not be connected to a network)

Whenever there are options to a machine, the smart developer will build the functionality into it and leave a flag for activation of said functionality if required. Hence why several machines may have the exact same program, but an OB or a DB will be different. One clear example of this on a company I worked on was the control station where all control stations would run the same program except the ID integer in a DB. Everything else was exactly the same.

As a standard, machines will have serial numbers and it doesn't hurt making that serial number part of the program or project file name... but that is at the discretion of whoever is in charge.
Also, remember that those machines may have been bought separately so the supplier never bothered to name the files differently.