A verified account option, one per person. Against people having multiple (troll) accounts.
It should show a little icon under each name/avatar.
Not sure how it should be implemented, one per IP, H/W ID, 2FA login?
Probably impossible but I know too little about this tech.
multiple account is not illegal...
if you do not spam and you have more specific activity on bitcointalk, i think it is legit.
for eample i know people who partecipate to many local child board... and they have an account for each nation...
for local child board i mean english, spanish, italian and so on...