Again I will say - even though there are some on the list that have great success at a dog park - I don't reccommend the use of dog parks for any breed - disease and no control of the other people and dogs. If you have Alpha basenjis - that just compounds the situation.
You need to train them seperately - because together you are NOT in charge. If you HAVE to go to a dog park - don't have both of them there. You will need obedience training and even then - an Alpha dog is an Alpha dog and they will do what Alpha's do - demand to be in charge.