In Arizona it is possible to have both the seller's agent and buyer's agent from the same realty. You must disclose this fact and the agency disclosure form ( to be signed by both buyer & seller ) we use does this. If the seller and buyer are comfortable with this arrangement, you can proceed. If either buyer or seller are not comfortable after full disclosure, most likely you should not proceed.
When there are really two agents involved, the form clearly states which agent is representing which client, however, the designated broker is still responsible for both buyer and seller. In this case there should be no conflict of interest because buyer and seller have representation and the two agents are obligated to their respective client and can be held resonsible through the Code of Ethics.