Not even a single "re-enactment" film should have been required!
Think about it:
Two armed robbers enter a bank and demand that the teller give them all the cash in their drawer. After they have the cash they tie the employees' hands together and put gags in their mouths before getting away. Luckily, the robbers wore no masks and the entire episode was recorded by a security camera. When the police arrive the robbers have vanished. Shortly after that the FBI arrive on scene since bank robbery is a federal offense.
Can you imagine the city police AND the FBI separately coming back days later to each shoot a "re-enactment film" of the crime? For what purpose would they do such a thing? They already have the REAL film of the entire crime in their possession.
If they already had the REAL DEAL on film a "re-enactment" film serves absolutely no innocuous purpose. This is particularly evident due to the fact that they shot part of the films from the exact location from which the REAL film was shot!
However, such an otherwise extraneous film could serve several "not so innocent" purposes.
[Below: Secret Service Re-enactment Film. Portion shot from the Zapruder pedestal is near the end of the film.]