Can the same target address appear more than once on transaction output?
There is no protocol rule which forbids having multiple outputs with the same bitcoin address. Here is an example of such a transaction:

https://blockchain.info/tx-index/16459554/3baf2227efd23449822e181372389af762c26a4567362ef174fa8659cf61eb20?show_adv=true

It is not common to see this as there is no point in having mutiple outputs when it can be done in one, it just makes the transaction larger and hence increases transaction fees.