A 57-year-old man with atrial tachycardia (AT) after cavo-tricuspid isthmus ablation underwent electrophysiological testing. Mapping revealed atrial activation with a cycle length exactly twice that of the P-P interval on electrocardiogram. Electroanatomic mapping revealed an AT focus near the left superior pulmonary vein, with inter-atrial conduction occurring in the lower septum and cavo-tricuspid isthmus conduction block. A propagation map demonstrated activation going down the left atrial posterior wall and right atrial free wall, generating different positive P waves in the inferior leads. The focal AT with inter- and intra-atrial conduction block exhibited widely-split P waves misinterpreted as a distinct AT.