Specific rules on two same-account characters in a city together?

I'm thinking about leveling a rogue specifically to open lockboxes. My idea is that I could keep my main Warmane window (the one with the box) running, open my rogue in a second window and have him join the first in a major city, and then have him open my main's lockbox.
Is this considered multiboxing? Would I need to make a second account for my rogue? I wouldn't use any multiboxing software or take my main and rogue into a dungeon at the same time.
Just wanna verify before I get banned for trying lol

Multiboxing is allowed, even if you use multiboxing software. You just can't have any more than 5 accounts connected at a time.

Nothing you're considering appears to come close to breaking any server rules afaik...but you will need two accounts. Only one character per account should be able to connect at a time...logging into the account with a second client/computer/instance should disconnect that account from the first client.

Perfectly fine by rules. Just be prepared for the random morons who say "reported bot enjoy your ban f***ot" like I get daily. People whispering me saying they're reporting me for "botting" makes my day. It makes me want to do it even more. It means they're too stupid to even set up for multiboxing let alone control it.