score:13
Not all were that ordered, and it may have been the exception rather then the rule, but it did happen:
Both men faced each other sideways in the dueling position and hesitated briefly. Then Tutt reached for his pistol. Hickok drew his gun and steadied it on his opposite forearm. The two men fired a single shot each at essentially the same time, according to the reports.[4] Tutt missed, but Hickok's bullet struck Tutt in the left side between the fifth and seventh ribs. Tutt called out, "Boys, I'm killed," ran onto the porch of the local courthouse and back to the street, where he collapsed and died.
The Wild Bill Hickok β Davis Tutt shootout
Note that from the sideways stance this resembled the classic style duel from earlier times.
For a list see this: List of Old West Gunfights. (Not just street gunfights, but many have their 'Hollywood' style reproductions as well.)