Game Genie multi-codes?

I added Game Genie back in my emulator. It's working. ^_^;;

What's the rule when someone wants to enter more than 1 code at a time? In the original GG, how many codes were acceptable? Can I enter a 6 chars AND a 8 chars codes? Two 8 chars codes? Two 6 chars codes?

What's the rule after all? I believe to avoid codes that points to the same address, for example.
I need some advice on it.

The original Game Genie supports up to three codes. This could be three 6-character codes, two 6-character codes and zero or one 8-character code, one 6-character code and zero, one, or two 8-character codes, or one, two, or three 8-character codes. I don't know what happens if you add two codes patching the same address.

If you want to see what the original game genie UI looked like, an NROM version of that is available on this site:
http://nesdev.com/genie.zip

Some people do actually chain multiple game genies to implement more codes, though, so in practice the limitations of the hardware have been occasionally exceeded in that way.

So, 3 codes, any combination. Thanks.

When I examined the writes the Game Genie ROM uses to send the codes to its hardware, the results I saw suggested the following: If you enter multiple codes for the same address, the Game Genie only uses the first one and marks the others as invalid/disabled.