You probably have a script that kickbans clones in a channel.
Another case, I'm not sure if that's what you meant. But if you mean that when someone bans a user, the bot will kick all users which match the ban; then you need to remove the +enforcebans from your channel's option by typing .chanset #channel -enforcebans in your bot's partyline. (if this doesn't work, then you probably have some script which enforces bans)
check your bot for existing users with +k flags matching that hostmark.
if you tell the kick reason, we might be better to figure out whats the cause to kb.