1. Having multiple bitcointalk accounts not abuse the rules ?
Not at all. Administrator Theymos also has 2 accounts namely
theymos and
theymos_away2. Let's say, if someone have 3 or 5 accounts, and he clear (5 of their accounts not breaking the rules and not participate in same bounty), for example :
account 1 for particapate on A signature campaign. Account 2 for B signature campaign. Account 3 for C signature campaign, etc.
its okay ? will not be banned ?
That is pathetic situation, when forum allowed the alt accounts , they were not knowing that in future people will be creating the account for just doing the bounty. Still what you are asking or planning to do or already doing is not exactly cause ban in this forum. But if you think logically how can you be constructive poster with so many accounts? Your post quality will suffer or you will start copying. You can be permanently banned from the forum as a person (not an individual account) for plagiarizing or for spamming (low quality post).
Anyway forum will not directly ban user for having many alt account but DT member sometimes tag people with all their alt accounts for shitpostin or cheating the bounty system.
PS: Forum allowed the alt accounts for security purpose. If you are not in secure connection and still want to access the forum then you can use alt account. User never use these alt account to do deal or transactions and these alt account give them mental peace even if the account is hacked due to unsecure connection they have nothing to lose as there main account is safe. You will understand later on how important "Trust" is in this forum.