Can the same target address appear more than once on transaction output? Normally, a transaction output will contain a list of address + amount.
Each element in this list has an associate output number, "vout".
For example:

Transaction outputs:

vout=0: addr=m111111, amount=100 
vout=1: addr=m222222, amount=200


My question is: would it be legal for a transaction output to contain
the same target address more than once?  Take for instance the example below, where address "m222222" appears in vout=1 and vout=2:

vout=0: addr=m111111, amount=100
vout=1: addr=m222222, amount=100
vout=2: addr=m222222, amount=100


I know this seems silly.  I'm just wondering if it is the sort of
thing one might encounter "in the wild".
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.