i am starting a new Main character, i didnt like my old one. can i lvl my main with my mule in same pt, as long as i stop mule at 10? i get mixed answers in game. i dont want to get banned, i love this server.

Only nas can tell you (and maybe if you can convince Nabutso to ask nas, because apparently he's able to talk to him directly).
But let's put it this way - By the time it took you to wait for this answer you could have solo-leveled your mule to 10 already. First 10 levels take only a few hours anyway if you don't take breaks.
Besides, leveling to 10 is not necessary and not needed (the only reason nas allows that is to remove the "?" icon) and a lot of people just keep their mule as level 1. It's your choice obviously but I wouldn't take the risk of a ban, even if it's extremely small, over something small like a question mark icon on a mule or a few hours of solo-leveling.

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He was talking about his mule.
Absolutely no problem with main and alt leveling each other, a lot of people do that. Also the name "main" and "alt" may also be a little misleading because there's no rule that says that your main has to be higher level than the alt or with more play time.